Interested to know how people would compare the two.
Shuttle is cheaper, more features, and rated at higher wattage.
The F500 is that MB tone I know I like.
Basically, I want something clean, quick, light, small, with a lot if headroom.
I've owned both. Here's my quick take...
Into a box like my UL310, the F500 (F1) is a killer. The UL310
has a wide sound stage so it matches well with the quickness
of the F500, that hasn't got really extended lows. Most of the
Markbass amps I've used do much much better at 4 ohms. The
UL310 at 5.3 ohms lets the amp do its thing.
The 9.0 into that same box is bigger sounding and almost as
fast, with more in you face at around 4K.
Using a smaller box is a whole other thing.
The 9.0 has more extended lows, so it can bring out as much
low end as a small box will allow. The F500 hasn't got the
extended lows of the 9.0, even though the specs would seem
otherwise.
Both amps are different flavors of wonderfull. I like them both
depending on the match up of speakers.