5751 tubes and Rogue Tempest?

12BZ7 is the ticket. Much better dynamic contrast and safe to substitute for the 12AX7 according to Rogue.

I think the 5751's sound much better and have a LOT more focus than the 12AX7's. The 12AX7's sound fuzzy in comparison. Have not tried a 12BZ7.

As I posted in more length in a similar thread, I preferred the RCA 5751 over the Telefunken 12AX7. The Telefunken was more dynamic, I guess, but 5751 seemed to give me a sweeter sounding system. But it wasn't so much the dynamics but rather the musicality and reduced noise that the 5751 gave. I describe it as like going from ultralinear to triode all over again. But whatever the actual proper way to describe it, I just preferred the 5751 and am happy with the dynamics of my system. And my system is plenty dynamic.

System:

Rogue M-180 monoblocks with RCA 5751, RCA 12AU7, Gold Lion KT88

Rogue 99 Magnum preamp with RCA 5692

Kimber KS-3035 speaker cables; Kimber select interconnects throughout

Silverline Bolero speakers

The system sounds fine to me.

Caveat: the bottom line is that you need to try a couple of the tubes you are considering and see how they sound in your system. What worked for me may not work for you.

Reynolds853...How did the GL 88's improve your system over the stock tubes? Were your stock tubes EH KT-90's?

Samzx12,

I actually never owned the stock tubes. I ordered the M-180's with the GL KT-88's - they were about a $300 upgrade from the stock EH KT-90's.

I would like to be able to give you a more insightful answer regarding the comparison of the two tubes, but I went with the 88's on instinct and haven't actually compared the 88's to the 90's. I asked the guys that own the local audio shop which they thought I should get and after talking about it they recommended the 88's. I don't recall the attributes they mentioned, but I have been very happy with the 88's. I do find that the combination of the 88's and the RCA small tubes I have make for a very musical system with a very low noise floor... I run the system in triode 99% of the time.

Sorry that I couldn't be of more help.