Dual Mono Tube Pre-Amps

I have tube mono-bloc amps and was considering changing out my pre-amp to a dual mono tube pre-amp. On paper it makes sense but is there really much of an audible difference? Also any suggestions for the pre-amp?

I have a set of Tom Tutay updated Altec 1570b mono-bloc amps directed by an Air Tight ATC-3 pre-amp.

First Sound Presence Deluxe II is dual mono. http://www.firstsoundaudio.com/deluxe.html

Call the owner, Emmanuel, and ask him your questions. He's extremely friendly and helpful.
I do believe that audible illusions modulus and MFA magus are both designed as dual mono units with dual volume controls. Both are awesome sounding. I hate having 2 volumes.
Dr. Klimo's merlin preamp from Germany. Not that well known here in North America but certainly a definitive statement nonetheless regarding "true" dual mono preamps. Sonically speaking it's top shelf and surely competition to the finest preamps anywhere.
VTL Ultimate is one of the best, has a seperate power supply, and is a dual monaural design. Priced right at just over a grand WHEN they come up.
I will second Tvad's recommendation. Give Emmanuel Go a call and discuss if your needs can be met. Great preamp.