Marantz 8 (8B)best overall, Mc225 well rounded and neutral for then, at about 25 watts. The Dynaco at 15 watts or so in triode(30wpc normal) doesn't sound that good in triode wired mode IMO. The ST-70 is best for its midrange, when run in it full output(pentode) designed mode. Most pentodes usually don't sound any good when rewired to triode. They(ST-70) were designed for pentode operation. The ST-70 has better mids (tossup with the 8B) than the Mac, but tubby bass, and laid back highs. The EL34 Marantz and Dynaco have a lot of tubes to choose from,for rolling. The Mac sounds best with NOS Westinghouse, and good with other Nos 7591s.I havn't heard one with the new 7591 tubes.