I love my SD60, I have s/n 7, with the ported cab. Killer amp. I typically run mine with a crunchy tone, rolling back the guitar for cleans, and stepping on something for extra dirt. I don't find it dark... the tone controls are very interactive, rolling back the bass increases the trebles. I don't feel it to be "Marshall-y"... I have A LOT of old Marshalls, they are not dark... typically too bright. In the old days, we used to joke that Marshalls had a bass control, 2 trebles (mid and treble) and a 'hiss' control (presence). The 4 input Marshalls were basically the 5F6-A circuit, but 6CA7's have an entirely different impedance than 5881's, different current draw, different PV, just different... which is why I think those old Marshalls are SO glassy. Almost as if the power section is MORE efficient, allowing the true sound of the preamp to pass. The Naylor is definitely got a Fender thing, as far as lows. The reason you keep the bass control on Fenders down, and ALL THE WAY UP on Marshalls is that the Fender circuit reproduces more lows. Now, don't misunderstand, I'm not talking about the quality of lows (tight vs. loose) BUT, I will contend that Marshall get their low end thrust (when turned up) due to the closed back, infinite baffle cabs. My brown tolex Super has very pleasing low end, it's a 2x10 combo. My 69 Plexi only sound good around 7 (both channels, strapped, me plugging into the bass side), which is deafeningly loud. If I plug into the OXBOX, it sound good, but still, you must have the volumes up that loud. The Naylor can give you great 'loud amp' sounds at a club volume, Very responsive, very tactile. NOTHING LIKE A MESA (thank god)... But I think the Marshall comparisons are somewhat misleading, at least compared to my 5 old Marshalls, that I played exclusively since 1988. Just my 2 cents.