I had a Pioneer Premier DEH930 that died. I replaced it with a Rio Car. I had some of the same concerns as you do about replacing my head unit. I know exactly what you mean about wanting a dedicated sub output. With MP3's, I especially need control over the sub because not all of the files are normalized the same. I'm still looking for the perfect solution but I think I've found something. The audiobahn (http://www.audiobahninc.com/index2.htm) AX202X crossover has two inputs for front and rear from the Rio and it creates a sub output with a remote knob that can be mounted in the dash. I've ordered one for $120 and should get it in a week or so so I'll let you know how it works.