Wanting to hear from those who have played on these, what is your opinion/impression, what did you plug in when you played on it. Strengths, weaknesses?
I'm looking for something to plug in both my uBass and my Blackbird Clara.
I owned the smallest Peavey Vypyr amp for a little while. I was drawn to it because of the claim of being able to do everything - Acoustic guitar, electric guitar, and bass - all with one small amp.
The smallest Vypre was a failure for my application.
Strengths: Heavily processed sounds for electric instruments.
Weaknesses:
1. Poor bass reproduction. Despite the claim of being designed to handle low frequencies the actual bass amp tone was very farty and distorted at any audible volume level. This was with a standard bass guitar. The U-Bass seems to present a more URB tone - bottom heavy with less upper harmonics - than a standard bass guitar, so I would not expect the Vypyr to sound very good.
2. Poor acoustic guitar reproduction. I could not find an acoustic guitar setting that sounded like my acoustic guitar. Over-processed, and I did not care for the tone. Call me narrow minded, but I want my plugged in sound to be just like the acoustic sound.
3. Usability. My Vypyr always started on the same heavily processed electric guitar setting. Then I had to navigate to something that sounded better. This may be OK if you like over-processed sounds, but it was not a good fit for me. I also found it difficult to get a good electric guitar sound.
I had previously owned a Fender Mustang 1, a small amp that I enjoyed every time I used it (however infrequent). Sadly I sold the Mustang 1 too soon after getting the Vypyr. I did not try to re-program the Vypyr - I was too frustrated with not being able to find the sounds I wanted. Then I sold the Vypyr. Cheap.
My advice is that you try the Vypyr before you buy. Guitar Center used to stock them. Use an electric bass and an acoustic guitar (or ukulele) in your tests. Turn the amp off, then turn it back on and see if it comes back to the previous control settings.
I have pretty good luck finding sounds I like from a Roland Cube 100 bass amp, both with bass and with acoustic instruments (guitar, ukulele, violin). It has a few effects built in and a DI, making it very handy for a stage monitor when you have a PA. I also use the smaller micro-Cube (battery powered) which sounds pretty good with a U-Bass considering it's size. I think both are a bit over-priced, but they work well for me.
Good luck, and please let us know what you decide after trying a few amps.