Could Class D really be that good?


I've heard statements praising modern class D amplifiers all the time but was sort of hesitant to try. Lately, one particular model caught my eye, the Fosi V3, which costs sub $100 but is praised for having refined sound like class A/B. To fulfill my curiosity, I quickly ordered one and tried it with my Burchardt S400II and Wharfedale Linton speakers. Basically, this is a neutral sounding amp but, to my surprise, the sound is clean, open, airy, with full mids, wide soundstage, good imaging/separation, with nearly null traces of the edginess, dryness, or lean sound that traditional class D amplifiers have. The background is just as quiet as my current systems. The core is the TPA 3255 chip from TI and comes with a 32v, 5A power block, which is supposed to deliver approximately 65 watts per channel (into 8 ohms). It drives the S400II/Linton without any hesitation, as well as my 130-watt-per-channel high-current Parasound A23. Very impressive.

Measurement is not everything. However, according to the lab test results, when operated under 10-60 watts, the distortion level (THD) is below 0.003%, better than a lot of high-end (price) gears. I am going to build around it for my fourth system with upgraded op-amp and LPS. I believe it will outperform my current mid-end (price) amplifiers.

I know, I know, quite a few Audiogoners' systems are above $100k, and mentioning this kind of little giant that costs a fraction could be rather embarrassing. But I thought this is just like gold digging with a lot of surprises and fun. Don't you think?

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I just bought a Nad c268, just to experiment with class D and to use as a second, or maybe third set up. I’m not using a conventional preamp, but instead running two sources into the amp. The sources, a Music Hall A3 Analogue phono stage, and a Smls Pl 200 top load cd player, both of which have their own volume controls. Thus far, I’m pretty well pleased with the sound, although not as good as my class A or class AB stuff (Sugden & Accuphase). I ended up buying a second Nad c268 to try bridging, as my Tannoys are a pretty stable load @ 8 ohms, and 89 dB sensitivity. I'll see how that goes. I'm hearing the cheap c268 has a warmer sound signature compared to its big brother, the c298, although that one looks real nice too. The Nad c268 has all kinds of options for its use, great versatility. Even ASR recomended it, lol. Not many reviews for it, as opposed to the c298. Guess I'm a guinea pig. 😃

After years of running different amp / int amp combos, tube and A/B solid state, I decided to try a low cost used Class D Int amp from Bel Canto S-300iu feeding ML Ethos. After 3 months I remain blown away by the clarity, imaging, (add other superlatives here)... My journey is over...class D works well.

I added a THD (%) scale, which corresponds to the dB scale, into the graph for comparing more affordable NAD C268 ($1k) and the Bel Canto S300iu ($2.5k) with the Fosi V3. As shown, the NAD C268 is comparable to the Fosi V3, but the Bel Canto is far inferior. Again, measurements do not mean everything, but the THD measure does give an indication of the sound clarity. I just provided you with the data in one place for your convenience, and it is your discretion how you interpret the data.