Yeah I love this exact setup too. It's just too heavy and I'm getting old. If I can't sell it all together, I'll just keep the Ampeg for now. It's a great sounding amp just doesn't have the power to push the volume an SVT does and I want my second amp to also be my backup to my SVT. My wife is not cool with me having a half dozen amps lying around.
The thing is with the preamp, the one dial has so much character that it's similar to eq. It's really just a character knob which helps depending on what instruments/mics you are using with it. I actually use it on the completely FLAT setting but I do like the tones you get out of some of the other settings. It does NOT have an EQ as mentioned by disasterline. Which means if you are using this as just your pre... you are going to need an eq. That's why I use this in the effects loop. Still get the gain and the tube sound but can use the eq on the Ampeg which I think is great.
I did a lot of research into getting a tube pre and read some good reviews on this so I took a shot. I can't believe you had the same thing. I guess great minds think alike. What are you playing now?