Wanted: Multi-Channel Audio Interface for iMac & GB (USB)

I am looking for an affordable multi-channel audio interface for my iMac for use with Garageband. My goal is to playback old songs from my old computer (Atari ST) through my Yamaha gear and record the audio into GB so I can mix it. (READ: Not interested in transferring MIDI.)

My goal is to get at least 4 and ideally 6 channel/track recording in GB. I’m not sure if the multi-channel units I see, such as the Alesis MultiMix 4 or the Behringer Xenyx Q802USB send all channels to the Mac or if they mix it down to two channels first.

I’d prefer to mix all the channels in GB rather than pre-mix it. Also, I’d prefer to have 1/4” jacks; XLR would be a nice bonus. USB; since Firewire is going away and Thunderbolt is too new.

Any suggestions? I’m trying to keep this under $100. (Also, I know I can use multiple low-budget devices and aggregate them in Audio/Midi, but I do NOT want to go that route.)

Thanks.