Tubes with different gain for Moscode 401HR

The outside position has a more obvious affect on gain. If you swap the 12AU7 to the outer position in the HF amp, you will notice a difference, IMO.

12AU7 tubes produce a wider, yet shallower image than 6922. It's also a touch softer in the top end and upper mids. This was a more musical sound, IMO, and it would explain why you find the sound better in the HF amp using 12AU7.

I am not bi-amping, and I no longer own a 401HR.

The solution may well be a Differential pre-amp, such as the Supratek Cabernet Dual, with different outputs and tubes to LF and HF. Yet more $$.........

Problem with the 12AU7 on the outside means you cant use the higher gain 6DJ8 tube with it, so there is no way of getting differential gain.

May I ask what amp you are now using, Tvad?

11-15-07: Springbok10
The solution may well be a Differential pre-amp, such as the Supratek Cabernet Dual, with different outputs and tubes to LF and HF. Yet more $$.........

Problem with the 12AU7 on the outside means you cant use the higher gain 6DJ8 tube with it, so there is no way of getting differential gain.

I don't know what that means. Are you talking about not being able to use the 12AU7 and the 6922 in the same amp, but in different positions? This can be done. If you're talking about not being able to use 12AU7 and 6922 in different amps because the gain will be inherently different, then this is true. I thought that was your goal?

Why not use a tubed crossover like a Marchand unit? I believe the gain can be infinitely adjusted this way.

I'm using a VAC Musicblock 160 monoblocks with an Atma-Sphere MP-1. I have Atma-Sphere M-60 amps on the way for comparison.

What I mean is that you cant use a 6 series with a 12 series in line - so if a 12AU7 is on the (LF) outside, another 12 series tube must be used on the HF (outside), (according to George) defeating the purpose of using the higher gain tube.

I too have an Atma-Sphere MP-1 and MA-2 in my main rig. The kings, undisputed. But in this system with Mark-Daniel speakers, (4 ohm, down to 2.8, 85 db sensitivity) LF must be driven by ss/mosfets, unless I drove them with the big Atma-Spheres, which I'm not about to do.

11-15-07: Springbok10
What I mean is that you cant use a 6 series with a 12 series in line - so if a 12AU7 is on the (LF) outside, another 12 series tube must be used on the HF (outside), (according to George) defeating the purpose of using the higher gain tube.

I see.

If it were me, I'd try it anyway despite what George says.

Otherwise, I'd investigate the Marchand tubed crossover.