If you just want 8bit 4channel tracking then a stock A1200 maybe + some fastram is enough. However, I would recomment a 030 accelrator + 8MB (or more) and HD or CF at IDE port.
If you like multichannel tracking and/or just play such tracks on your Amiga then additional a 060 is a must and for 16 bit a sound card.
A faster filesystem like PFS or SFS is good for better file (samples) access. SCSI, Fast-ATA or a IDE card make this more better.
You know OctamedSoundStudio can do up to 64? channels and it profit from a large screen solution. Btw. using monitor MULTISCAN:Productivity (60Hz 30kHz) might work on any TFT monitor without extra hardware (flickerfixer, gfx card, ...). Needs just a proper cable.