Bi-amp question

I agree with what the others have said. Even with the exact same amps, my experience is that 3 out of 4 cases the benefits aren't worth the effort and cost of 2 amps - you're better off trading in your NAD for a better amp.

I'm doing vertical passive biamp on one of my systems and it does perform better than other single amp configurations, but the speakers are unique in that they take advantage of it. I've tried other speakers and amps with near zero resultant benefit. I also tried horizontal biamping using tubes on the top, ss on bottom - it was simply too much effort and trouble for the benefit. My speakers sounded better using the tubes full range.

03-11-12: Kr4
"I'm doing vertical passive biamp on one of my systems and it does perform better than other single amp configurations, but the speakers are unique in that they take advantage of it. "

Can you explain how the speakers are designed to take advantage of passive bi-amping?

yes, with hindsight I can see that deserves clarification. Indeed if I hadn't posted that in such a hurry I would have reworded it. I don't speak with authority on this - it's simply my experience, with my system.

I don't know how, or even if thay are designed to take advantage of biamping. They are Von Schweikert VR4GenIII's with 2 separate modules (Bass and Mid-high), each with its own crossover. When I was deciding on amps for that system I called Von Scwheikert to ask them for advice. Albert Von Schweikert answered the phone personally (on about the 3rd ring). The question I asked was "Will they perform better with vertical biamping, or with a more powerful single amp?" . . . or some wording like that. Albert went on to talk at length about the VR4GenIIIs and biamping. He first said 2 identical amps vertically biamped would out perform a single higher output amp. He further advocated running tubes on the top, SS on the bottom.

I experimented with multiple amps both biamp and non. Tubes on the top, single tube amp full range. This is how I reached my judgements. I like the vertical biamp arrangement that I have now best of those I tried. The setup I ran with tubes on the top was getting too complicated so I abandoned it. I tried single amps costing more than the 2 amps I have now; however I have not tried all of the amps, just quite a few ;-) .

I have also tried biamping on other speakers. Passive vertical biamping using Totem Mani-2s (in my other system) was fruitless (just as Totem's Support rep told me it would be). When I say 3 out of 4 tries weren't worth the effort, I mean it literally. That's how many systems I tried. For me though it was about learning/experimenting, just trying different stuff..