how about using two NAD c352? It have 2 pre-outs so you can link both and still have 1 spare pre-out that you can use for the sub or .1 plus the 4 speaker terminals. That should now be 4.1? I actually hoping this setup for a stereo mode for bi-amping since its the only thing i can buy at my place and c352 have excellent user feedbacks and reviews.
if i do it i'll probably use 2x nait5i or unico. but the 352 is a good amp, owned one last year. why not get the 370 rather than bi-amp with two 352's? have you got really inefficient speakers that one 352 is not enough? its drives most speakers easilly.
Im just hoping to delve into bi-amp sometime in the future. Since budget is tight, i have to plan my purchases ahead of time. I just about to buy my first c352. So maybe i'll explore that 370 later when i have the itch and budget to upgrade my not yet bought c352 (which i will within the next two weeks, hopefully.)
Sorry I didn't get to your question when you emailed me Roderick. I've been involved in a home remodel and only have brief moments to look at the forum. I've not heard of biamping with 2 NAD integrated's. Bridging 2 for high power mono operation yes, but not biamping. So in other words I'm not sure as I am not using NAD gear anymore since I discovered tubes. Good luck.