The Rubicon Black Gate caps I used for the power supply are a great way to nail deep bass lines. They are so quiet the bass jumps out at you. Unfortunately they take up a lot of real estate. I had to stagger mine up and down on the board to make them fit right.
You will find one pair of caps in the direct signal pathway. I used teflons here. However a pair of Mundorf Silver in oil would have deeper bass and great mids.
I have to have air up top to be happy with my gear, so on mine the FT-2 teflons rule the day. Dang these things are clean and clear.
In the final analysis, I have all the detail and precision of an SUT but with less sibilance, better bass, and a super quiet noise floor that defies description.
When I crank things up without a signal, all I hear is tube rush from the Cornet 2. Thats about the best testimony Jim Hagerman could ever expect to hear about his design. Every other head amp I know interjects white noise or sizzle and I am including the big guns like the Klynes.
This is the quietest head amp I have ever heard and Jim Hagerman is a genius! Don't forget to try some TI shielding across the power supply pieces like I used. TI shield is amazing stuff for audio projects when it comes to draining emi noise. Its so good that HP uses it in a great variety of sensative test gear.
Cheers!