Are EL34 based amps more musical than KT series based ? Or it's purely a matter of design?

I think it’s hard to make an EL34 not sound sweet. You have to really mess it up. The larger KT tubes will (by comparison) give you brute force, dynamics, impact - but it’s hard to keep all that while getting them to sound as "sweet" at the same time, as the smaller tubes which seem to do it so naturally (EL34, EL84, 6L6’s etc). I think VAC’s recent high-end lines do a GREAT job at that (plus next-level articulation and refinement), but takes some doing and ain’t cheap.

Vintage tubes amps are a lot of fun and a nice break from the "hifi" sounding amps because they’re so inherently musical. Part of that, I think, is the use of those tube types. But there are those limitations - power, and usually bass impact / dynamics.

300B / SET DHT bug hasn’t bitten me yet - it’s nice but I’ve heard no special magic I "gotta get". To be fair I like to listen louder than most audiophiles, and with more hard rock; the power limitation can cause some nastiness at higher SPLs.

I met Kevin Hayes at Sound by Singer (early 2000s), he opined that the 30/30 might have been the best sounding amp he had ever designed, but it was not a commercial success, he could not sell it for a price that was profitable.

I’ve heard exactly that about the VAC Renaissance / 300B lines, from multiple sources. They’re still sough after. The monos generate more power than most, and might be right up my alley, but I haven’t gone there yet.

But it’s also been a while since those days, and I can say that VAC’s KT88 based amps have come a long long LONG way since the past, even the 2000s (I used to have their little Auricle monos) - in both sound and price :(

RM-9 wrings quite a bit out of EL-34 but Roger was a genius… Like Gordon Gow and the 6L6 MC240… but really no meaningful conversation is possible without also considering the massively important imo ….output transformers….

@tomic601 I’ve always surmised that the MC240 would sound amazing to me. 40 watts is juuust close to enough for my needs :) I might have to try one some day. Yes, output transformers are crucial - avoid the bad ones - a lot of the good-rep vintage amps are renowned for their OPT’s (even Heathkit and Eico used Acrosound, Peerless). I imagine this is where the Chinese tube amps typically skimp. Some of the later Carver amps also got exposed for way undersized OPTs.

Then maybe I should upgrade output transformers in my VAC Avatar with custom ones ? This is a crazy idea, I think.

Inna case this was serious - don’t do this. You’re not going to out-expertise nor out-voice Kevin Haye’s choices for his own amplifier. You can certainly out-budget him within the context of an Avatar SE, but at that point - just explore any of VAC’s newer, more advanced models released since the Avatar.

"Then I can’t use my Mullard EL34". Yep! Them’s the breaks. Kevin’s done wonderful things for KT88 tubes since then (pricey, though).

Final thoughts: don't do this.