Its ok if you use a SS amp with a tube pre or vice-versa. The only issue you might run into is an impedance mis-match. I'm running a Quickie with a large SS amp that has a 10k input impedance (Quickie likes to see 50kish). There was a workaround though, soldering in some 100k resistors into the signal path between the input switch and potentiometer. Depending on the relationship of input impedance to output impedance in your system, this may or may not be an issue (but is fixable!). You probably couldn't go wrong with either the Beepre or smash (i believe both are SET, and so is the Quickie!). Don't know as much about these two, but the Quickie is pretty impressive itself, and SET is very nice (the smash is supposed to have a little bit more realistic tone than the quickie). Maybe someone else can chime in on the differences between smash and beepre.. One thing though, is that the smash has 2 sets of outputs, so if you run a sub, that can be pretty handy. Thanks,
Dave