Re: SLO-100 and Bogner Metropolis MP3's
No, I don't use an attenuator.
The SLO is pretty loud, but very linear in the response of the volume pots. You can get good tones at low volumes. Actually, the SLO was better at low volumes than the 8440 I used to have.
I have had the SLO since 1991. An SLO sounds like an SLO. Its not a Plexi copy, or anything like that. I have never come across another amp that produces such fat and defined single note leads. The XTC is more versatile with 3 channels, and the various settings. Its awesome in fact. But, it does not trump the SLO in this regard.
If you get an SLO, get one with the Warren Haynes fat switch. That'll make it so you can use lower gain settings on the overdrive channel, and its very warm & woody sounding.... very sweet. The depth mod is cool, but I don't use it as much. KT66HP's are also good... very fat and warm. Clapton used 2 SLO's on stage for a few years. He and Gary Moore were both using the clean/crunch channel.
ALSO, if you are interested in a Soldano, then get the SLO... it is worth the extra coin. The other amps DO NOT use the DeYoung Manufacturing transformers. The Decatone, Lucky 13 and others have the same circuit, but not the same trannys, and there is a difference. AND, SLO's are very sensitive to bias adjustments. The pot is inside the chasis. The amp is so overbuilt that you can set it at any level, and the amp will be okay. But, I found that this particular amp, with the KT66HP's sounded best biased at 32.5ma, which is actually kind of relaxed (ie. not really hot bias setting). Mike & Bill are easy to talk with, by the way. They'll do all kinds of mods if you so desire.
Randy