Ok so I decided to break down and buy a rackmount amp on the cheap, it's a B2 (an older version of the B2R). I know there are a lot of haters of these smaller amps on these threads but it seems to have a good enough sound and power for my current playing situation. Anything was a step up from my BA210SP. I run this into an Acoustic 115. Wanting to warm up my tone in a more natural way than breaking down and buying a VT bass I decided to get a tube preamp. Finding an ART TPS II on the cheap, got that as well and put a new old stock tube into it for some warmth. Now this is where I need help. I rackmounted the puppy but I can't really use this as a preamp because when running this into the POWER AMP IN it disables the preamp circuitry of the Ampeg head thus rendering the tone knobs and EQ useless. I actually like the EQ on the amp and find it rather ridiculous to have to buy an EQ to run through the effects loop if I want to run it like this. My first question is: With running this tube preamp into the POWER AMP with a lot of gain do I risk damaging the unit? I thought I might so I unplugged it. Then I tried running the ART TPS II into the effects loop. The good news is that the EQ and tone knobs are not bypassed obviously. The bad news is I have no idea what impedance setting to use becuase I am running it through the rear balanced 1/4" and I don't know if this is dangerous or not. Is it? When running through this input or the front XLR inputs it enables the impedance control on the front. When running through the 1/4" input on the front, it disables the impedance. Is this what I should be running from instead from the effects loop or is there another option for me? Here's the manual if anyone is confused. I know I am. http://www.artproaudio.com/downloads/manuals/omtpsii.pdfhttp://www.artproaudio.com/downloads/manuals/omtpsii.pdf Thanks!