      Alesis Studio Electronics surfaced in the late 80's with some price breaking products aimed at the home studio. I personally bought several of these products and still use the Mixer for one of my groups. All the products are reasonably reliable for the money except the mixer which gets dirty easily. The compressor is noisy. The other stuff works well from what I've seen. All 'issues' I've seen with these things save one nanoverb, were related to bad wave solder! Resolder the board, it works.
      They entered the synth market in 1993 with the "Quadrasynth QS-4", breaking ground in the price/polyphony area. Cleverly laid out and interesting digital synths for their time. The QS series progressed to the QS8 weighted series; all of which are very similar to identical to QS7 and QS6 series products using a 'point something'after the 6,7,or 8 to designate the version number basically. IE 6.1 and 7.1 are the same product with different numbers of keys.
      Then in 2000 the 'Andromeda A6' emerged as the first real analog keyboard to be mass marketed for a decade or so. Fabulous 16 voice machine. Also I still use their D4 drum module because it has a great pad interface for my old simmons kit. The DM5 enhanced version doesn't work as well on the low output triggers. I'll create links below when I have time. In the meantime lots of resources are still available for these without much digging I think. For QS 6,7,8 and QuadraVerb2 sysex information, go to youngmonkey.ca

Products:

All Effects QS-4 QS-6 QS-7 QS-8 D4 Drum Module DM5 Drum Module Andromeda