My Single Rec is gone... But still have the SLO.
I am no pro, just a weekend player of about 25 years. I tried every Soldano I could find for a span of a year. Never found the same dynamic in other Soldano amps. The DeYoung trannys have something to do with it IMO and the opinion of the various shops I hit. SLO is absolutely a loud playing amp or don't get one. The MV needs to be past 3 for the amp to breathe and hit that SOL famous grindy growl. It sounds OK at bedroom practice levels but IMO you need a big room and some volume. At volume there is more pop or roundness in the notes (not too compressed like modern hi-gain Rivera). Did not find that same lack of compression on my Rec, your Rec may differ a little. The SLO loves to be cranked loud as hell. IMO the power tube distortion works well on the SLO, MV at 6 is where it gets really crazy good, need a large venue or iso-cab. My experience with the Rec when MV cranked 3/4 full is that the power tube section distorting was not good, seems to my ears it is a preamp distortion amp. Good clean and cranked type of non-MV amp tones to be had.
Would not say they are real close. The Rec I had was a more grainy distortion. Like comparing 60Hz to 400Hz on an oscilloscope, very tiny graduations between wave peaks. Tighter and smoother, more Mark Series in that one regard. I think it covers great Marhall based tones and does great bluesy cleans/grit. Goes great with a strat and working the volume knob a bit. The Rec could be worked like that a bit, but the voice of the amp was more toward pissed off metal to my ears. It would do it, but the voicing of the amp was not what I was used to hearing or wanted my playing to sound like.
The SLO is a strong midrange amp designed to be played loud as hell without being scooped. It will make you cut thru a mix very well. It is not an unforgiving amp, you will just be heard more clearly. It is too expensive to just buy over a GAS attack. I would play one for a while to see if you really want it. It is called a one trick pony unfairly. One trick gutar players call it a one trick amp. It just does the crunch and leads so well, you may not ever want to do anything else with it for a while.