No doubt about the asrx-pro!
Back in the day (90's

) I owned the black one new (saved every penny I had, f'ing insane purchase for me at the time). It's seq was alright. Several years ago I missed the old asrx (which I sold to purchase some bit of studio kit I can't even remember... wait, maybe an alesis Q8... if so pretty stupid) so picked up a used pro.
It's seq is totally bizonkers, like it chokes with very slight strain. It's seq is not useful to me in anyway. Maybe for like the kick snare of a boom bap. Maybe it's my unit. I def remember the black one having tighter timing. My pro needs tlc.
It's volume knob got a little busted in the latest move. I've never been able to get it's internal zip drive to work properly, so major workflow problems there. Some of it's buttons are sticky, and the worst part, the pads are like totally blown out. I mean they are still playable, but they're pretty much rock hard. I think the springs could be switched out in there too, they seem pretty maxed out. I DO love the sound of the asrx pro though,
no doubt. In honesty though, the asrx is pretty clean sounding. It is thick as fuck, but it's not dirty enough for my tastes. But I can def see wiring up the sx to the asrx and bouncing back and forth.
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But finally got my sx in the mail today. I'm sick as a dog and still grinning ear to ear. I'm sitting on my living room floor, my daughter sleeping on the couch behind me, and I'm just bouncing stuff back and forth between my laptop and sx, AND AM LOVING IT. It's definitely got it's own sound. It's pretty hypie, pretty brittle in the high end. I'd relate it to the mpc 2500, but defiintely a cheaper even thinner sound. I'm not hating. Everything's got it's own sound, and the sx seems to have it's own.
But I am just loving slamming fx down, resampling, and bouncing back and forth from lappy to sx. I can already see that this little box is going to
blow open up new avenues in my artistic explorations.
RE the 303, I just love that sound though, it's got it's own sound and I really REALLY enjoy it. Having an sx and a 303 wired up together would be a seriously ninja combo. Maybe there is a 303 in my
distant future...