Compatibly between Tubed and Solid- State Gear

I recently switched from tube amps (Audio Mirror SET 45) to solid-state (Nuforce 9 V2 SE). I am driving the amps directly from a tubed DAC (Lector Digicode 224) which takes its digital input from a Tact 2.2 XP preamp. The problem is that with the Nuforce amps, I am getting an excessive amount of hiss, hum, and other noise; although there was some noise using the tube amps, it was much lower and very tolerable. The tubes in the DAC are relatively new. When I switched to a solid state DAC (Muse 296) or use the DAC built into the Tact preamp, the noise completely goes away.

Any ideas why there is so much noise when using the tubed DAC with the Nuforce amps? Is there some basic compatibility issue between tubed and solid-state gear?
Some tubes are noisier than others. I've made it a habit to only install tubes that have been tested, and certified/graded, "very low noise" for use in any stage before(or in) a preamp. Lector also hand picks low noise and matched tubes for use in their DACs. ie- Read the grades in which this tube is available: ( If you have 60 cycle hum(in addition to tube rush), you might try floating the ground on the DAC. This is off the subject, and not related to your noise at all, but- are you using a MauiMods power supply in your TacT? You've not heard what the TacT is capable of without one.