Hi Korhan,
 > instead of buying 4 modules (two mixers for 8 steps), I'd go buy the A-155
 > right The 155 costs more than the total of those 4 modules but it offers a
 > lot more. Right
Yes and no. The mixers still also can be used as mixers, and the A-161
 still can be a nice trigger generator (e.g for miniature beatboxes with
 resonant filters), whilest the A155 will stay always a sequencer.
 Nevertheless the A-155 (especially in coopertation with the A-154) is a
 very recommendable tool, if you want to go in the direction of
 electronic music.
 Florian