Hey Audio Review dudes and dudettes,

I have a some components, concerning which, I would like some advice. Here are the units in question:

1. NAD 3150 integrated amplifer
2. Pioneer VSX-D1S receiver
3. Pioneer Elite VSX-99

Each unit has it's own challenge. The NAD's amp section doesn't like to send a consistent signal to the right channel (cuts out, sounds staticy, etc- plus it sounds a little "tired") so I use it as a preamp to the VXS-D1S. Obviously I use the VSX-D1S's amp section to push the signal to my speakers. Sadly, this is the only way I can utilize the D1S because the preamp has a buzz in the right channel (what the hell is it with my and the right channel in my equipment? ha ha). The VSX-99 is a kick ass unit but only (digitally) supports ac-3 and one digital input marked RF. What, pray tell, does that mean? I bought all of these units used and have had no luck in locating a manual online. My goal is to be able to use each of these pieces independently and have "islands 'o sounds" throughout my gf's and my apt. No, but seriously, I love swapping components to hear the different layers and textures that each supply to the signal chain (much to my gf's chagrin- ha ha).

My question is this (and thanks for hanging out this far): Is it worth putting, say, $200 into each unit to at least get it back to spec? Or am I better off putting my dough into a newer used piece? I am going to get a couple Onkyos for my HT systems so surround limitations aren't much of a concern.

Thanks for your time folks,

J