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ag TWS04K Review – More than a Rebrand

Pros –

Excellent accessories and quality case, Improved build quality, Comfortable and compact shells, Tasteful bass-boosted signature, Waterproof, Excellent battery life

Cons –

V-shaped sound will no longer appeal to purists, Large charging case, No wireless charging, aware mode or app

Verdict –

The TWS04K nails the fundamentals of a non-frills wireless experience, remaining a strong value proposition despite the price jump.

Introduction –

If you follow any audio distributors in Asia, you may have come across the brand ag. Operating under Esnext Co. LTD, the same parent company who owns and runs Final Audio, expectations are high. ag specifically target a lower-price point and innovative wireless form factors. I was unable to fully translate their Japanese material, but it does appear as if ag is doing so through collaboration with other manufacturers who provide the base design, upon which Final Audio complete the final sound tuning. At present, the company offers 4 models internationally, 3 TWS earphones and one ANC headphone. The TWS04K is their highest end TWS model targeting a well-balanced sound and huge runtime up to 180 hours. Immediately, what struck me here were the clear parallels between this model and the Lypertek TEVI which remains one of my most recommended TWS models. I was very curious to see what finishing touches Final had added to further improve this design and as I’ll touch on below, this is much more than a simple reskin.  

The TWS04K just launched in Australia for $199 AUD. You can read more about Ag and browse their selection on Addicted to Audio.

Disclaimer –

I would like to thank Rachel from Busisoft, IOPR and the team at ag very much for reaching out and providing me with the TWS04Kfor the purpose of review. All words are my own and there is no monetary incentive for a positive review. Despite receiving the earphones free of cost, I will attempt to be as objective as possible in my evaluation.

Contents –

Specifications –

  • Bluetooth: BT5.0
  • Codec support: aptX, SBC
  • Chipset: Qualcomm QC3020
  • Frequency response: 20 Hz – 20 kHz
  • Runtime: aptX up to 6hrs, SBC/AAC up to 9hrs, 180 hours including case
  • Water ingress protection: IPX7

Unboxing –

From the outset, the refinement from Final Audio’s backing can be appreciated. The unboxing experience is great and, as usual, the company provides a thoughtful set of accessories of impressive quality. Opening up the box reveals the earphones and charging case within foam with the accessories in a separate box below. You get papers and a short Type-C charging cable. The TWS04K comes with Final’s popular E-tips which are easily a personal favourite in the wired IEM world. They are now widely included with IEMs from other brands due to their unique and comfortable design.

These are actually a new design, modified for the TWS form factor. They have a shorter stem and a wider bore than standard E-tips. However, they do retain the signature flexible sound tube that provides a more personalised fit similar to Spinfits. As the elastic mechanism doesn’t obscure the sound tube, I find them to colour the sound less in so doing. Eartips can really make or break a true wireless earphone as they lack a cable to stabilise the fit. These are some of the best sealing tips I’ve tried, and I would gladly purchase them separately.

Design –

When I saw the first press images of the TWS04K on social media, I discounted it as a rebranded Lypertek TEVI. Indeed, even in person, the shell design is identical and even the weight is only 0.1g off and most of my comments towards that model also apply here. This is a compact, chic and stylish earphone with an exceptional IPX7 ingress protection rating making them waterproof and a great choice for workouts. I do think the TWS04K feels about one generation of refinement ahead of the TEVI, a quality you may miss in photographs online. The finish is uniform, the TEVI having an odd dual-finish complexion, and it has a more tactile frosted texture. The tolerances are about the same with a palpable seam between the two halves but no sharp edges that cause discomfort.

The overall feel and density is the same, meaning though they are entirely plastic, their construction lacks any hollowness, feeling more substantial than most competitors. The docking mechanism, nozzle, controls and mic placement are all identical. The ag does have a slightly different mic cutout and the shell is more squared off at the rear which I do find to aid the fit. Other refinements to be enjoyed are the new ring lights running the perimeter of the faceplates that look fantastic when docked. Though the faceplate buttons still aren’t my preferred location, the actuation force here has been reduced so pressing them no longer upsets the fit as much. It’s the many little touches and refinements here and there that showcase ag’s proud backing and the experience of their design team.

Fit & Isolation –

I was quite shocked by the fit experience too, which is markedly better than the TEVI despite the highly similar silhouette. Altogether, they are about the same size, being one of the smallest TWS earphones on the market and suitable for smaller ears as a result. And much of the ergonomic improvements here can be attributed to the new tips which give me an excellent, consistent seal, in addition to the well-angled and elongated nozzle design. However, even swapping the new tips onto the TEVI, I noticed the experience still wasn’t quite the same. I would attribute this to the slightly more squared off tail end of the housing that does achieve a snugger fit than the rounded TEVI for my ears.

Combined, I found them noticeably more stable fitting than the TEVI which was my main complaint with their ergonomics. Do note as well, the TWS04K doesn’t suffer from driver flex as the TEVI does, which could be suggestive Final either changed the driver or the surrounding acoustics. But returning to fit, I was still required to adjust them once or twice during my regular 6k run but I felt completely confident in their fit during my strength training routine. Isolation is strong and easily suitable for daily use and commute. While ANC models do block a little more low-frequency drone, I didn’t miss it too much. I found the stronger seal provided by the E-tips made them a slightly better performer here than the TEVI as well, itself a good performer.

Charging Case –

Here’s where the real changes begin, the charging case boasts a completely new design and is a huge improvement over that included with the TEVI. It is markedly heavier, more squared and a little wider but also slimmer. Though neither are ideal for pocketing, the new case far better justifies its size and rewards with a substantially nicer in-hand feel. Instantly, the supple faux leather exterior impresses. It promises to be stain resistant and hard-wearing, and certainly appeared so, especially by comparison to the fabric case on the TEVI. A single front-face LED provides a minimalist aesthetic but doesn’t provide the same feedback as the 4 LEDs on the TEVI case – though the ring lights on the earphones themselves do help here to some degree. The hinge is a huge improvement as well, with zero wiggle and a satisfying reverse magnet mechanism.

As before, the earpieces themselves are held in place reliably with strong magnets and connection to the case was also reliable regardless of tip choice. This is a big deal for me as many audio-focused TWS earphones do not reliably power off when docked due to either poor cut-outs or contact design, and the TWS04K was very reliable in this aspect which simply makes it nicer to use day to day. The case charges over Type-C and has a 2600mAh cell. Interestingly, it can also function as a power bank for a smartphone which is a smart addition for daily use and something I haven’t seen before from competitors. However, the case does not support wireless charging which is a strange omission given it has so many other thoughtful features.

Usability –

The TWS04K is a non-frills, audio-focused true wireless earphone and that’s not a bad thing depending on your priorities. For instance, as passive noise isolation is quite good, you don’t really miss ANC and other issues such as wearing pressure and artefacts aren’t a concern. On the contrary, a few small features that would have been easily added to improve the daily experience are also omitted. There is no aware mode nor an accompanying app, meaning there are no sound customisation options. While some competitors do offer these features, it is not something I would necessarily expect at this price point, and I would be concerned that other sacrifices may have been made had the TWS04K tried to cram in more smart features.


The TWS04K enters pairing mode when it is first removed from the charging case and can be manually paired after by double clicking the faceplate button when it is not currently connected to a device. Like the TEVI, the two sides appear individually in the pairing menu but the other automatically connects to the source once the first side is paired. Similarly, the earphones can be used in mono and retain full functionality. Once connected, I found the TWS04K to offer a reliable and artefact free connection both to the source and between the two sides.

Latency was minimal with barely noticeable lip-sync similar to other aptX touting models. Over longer ranges, latency increases and it also depends on the codec support of your source device as I did notice it was higher from my non aptX supporting Windows 10 laptop. This makes them a great choice for multimedia consumption and casual gaming on aptX devices. Range was an above average performer; I was able to traverse just under 2 rooms with double brick walls before signal became intermittent. As always, range will be substantially longer with a line-of-sight connection.

Battery Life

The strengths of the TEVI platform carry over when it comes to batterylife, with the TWS04K sharing its huge 10hr runtime rating, or 6hrs over an aptX connection. Paired to my Xperia 5 II using aptX and at low volume around 3 of 30 notches, I was able to beat that figure with 7hrs of runtime and a reported 10% charge remaining. This is a good result that bests most competitors and will last most a full day with only a quick charge break. The case as well adds a whopping 170hrs of playback time which is over double that of the TEVI.

Altogether, you can use these all day, every day for about 3 weeks before the entire system needs topping up. Unfortunately, they do not support quick charge and it is reported that the case takes 4hrs to charge from empty – an understandable trade-off given its capacity. While it isn’t mentioned in the listing, I did find the earphones themselves to top up quickly, about 50% in just 15 minutes, similar to most quick-charging competitors despite this not being advertised.

Call Quality

I was hoping that, with the new mic cutout, the call quality would be improved over the TEVI, but the result overall is similar. Recipients noted I sounded clear, immediate and loud with a good sensitivity. However, ambient noise cancellation was conservative making conversations in louder places difficult. It isn’t a bad performance and does in a pinch but is not an earphone I would want to use like a headset such as the Huawei Freebuds 3 or Airpods range as a result.

Next Page: Sound Breakdown

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