I built these a few years ago and always felt they lacked something. The amps where just upgraded, mostly the power supplies. Now filter caps have: 60-110-75-50uf and 800v. Also changed Sovtek KT88's to Electro Harmonix 6550's. These new (?) amps kick ___ . They are capable of 80 watts RMS, with 535V B+, (measured with true rms meter and oscope, 4 ohm load, 4 ohm tap). Using hammond 1650R's, 100w OTs. Bottom end seemed loose, uncontrolled, but now the bass is very impresssive. I am currently listening to Maroon 5, Mickey Maddon's bass finally has authority.
Shannon, Love the Poseidon boards. Here is a pic.