Bi-amp befuddlement

Newbie in midst of modest upgrades to old system and wondering if I am getting best benefit from bi-amping:

Having read about it, I acquired an Arcam 8 power amp to pair with my Arcam 8 Integrated.

Speakers are B&W 601 S2, about 20 years old, which sounded quite warm and nice bi-wired with Monster cables. For the bi-amping effort, I bought Anti-cables.

I followed the Arcam instructions and wired the power amp to low end, the integrated to high end. Frankly, not sure I noticed a difference - except maybe when I crank it up. The sounds seems clearer, with less distortion, or maybe that's wishful hearing.

I am questioning things in part because the other day, I shut down the power amp and the music nstantly went tinny, like some tranmission from space. Put on the power amp, and all richness floods back. Clearly, I expect a change but not such a massive one.

Is that normal? Is that all I am getting out of the intergrated? I have looked at Audiogon forums and read about vertical bi-amping - one amp per speaker. Is that a better use of two amps for somebody who is not going to mess with speaker cross-overs?
To reap the benefits, you needs two amps of the same type or you will have to buy an attenuator to adjust the volume on one of these amps.
If you are actually, "bi-amping" and you turn the amp off that's powering your bass drivers: guess what? All that you will hear is the integrated, powering the mids/highs(only the output above the crossover frequency). YES- It WILL sound VERY thin. What you've noticed at higher volume levels, is the main objective of bi-amping(clearer presentation, better dynamics and less distortion).
Thanks Rodman.

I guess I was shocked by the disparity. I expected a division of sound, but not so huge

Ajax, I figured two amps of the same power from the same maker are gonna be closely matched.

Any thots on going vertical option - one amp to each speaker? I guess I'll have to play around to see what sounds best. This weekend, I hope to listen to some used Snell and Theil flood-standers as possible upgrades, which could make things even more interesting.
The amps you have are a close and perfect as you can get match without going with a seperate pre amp and two matching amps. Your doing the right thing . Your 20 year old speakers if upgraded would be something to conscider if you really want to hear a differance. Cheers
You are correct in assuming that the Arcam amps(same power) will be matched, and you don't need further attenuation. You have to realize that the crossover point of that system(601 Series 2) is at 4kHz, and very little music actually exists above that freq(that's why the difference seemed so huge with most everything below that gone). Bi-amping with a much lower crossover point(say with Snell 3 ways); the disparity would not seem as great. I would stay with the horizontal configuration, as there will be a pair of interconnects on one channel and not the other, if you go vertical. That may cause somewhat of an imbalance in your presentation.
Rodman makes excellent points, but on the question of horizontal vs. vertical biamping, there are arguments that can be made both ways. See the comments by the noted designer Steve McCormack, favoring vertical biamping, in this thread:

Ultimately, of course, the tradeoffs will be system dependent, and the only way to judge what is best for your particular system is to try it both ways.

-- Al
I had not been biamping for some time , first because I was using my M3 and didn't have a good match for it and then because I was comparing my Spendor SP1/2s to the Mini Utopias which have only one terminal. A couple of days ago I decided to biamp the Spendors with 4 of my Meridian 605s. I had forgotten how much better biamping is, things stand out without straining to hear them and you hear things that were not there before. The Spendors cross quite high also but difference biamping is considerable.
If you were going to vertically bi-amp with separates(pre and two stereo amps), I wouldn't have mentioned any POTENTIAL imbalances. When/if you DO try that configuration; please post your impressions.
I had always been told that to get any real benefit from bi-amping you need to disable the speakers internal crossover and use an active external crossover. Yet the posts here suggest otherwise. Can anyone enlighten me on this point?
I had always been told that to get any real benefit from bi-amping you need to disable the speakers internal crossover and use an active external crossover. Yet the posts here suggest otherwise. Can anyone enlighten me on this point?
Benefits can definitely be gained without an active crossover. It depends greatly on the design of the speaker, and the amps. The best (and most authoritative) info I've read is in the thread referenced in Almarg's post above.
My experience has been mixed, with multiple amps, horizontal and vertical, and multiple speakers. In some cases the results were significant improvement, in some a degradation. If your amps aren't identical it's a pain to get them adjusted, and probably not worth the effort IME unless you use an active crossover. And, though I haven't tried an active crossover I suspect it's hard to set that up and have confidence you've optimized everything - sort of like setting up a home theater.
Thanks Bdgregroy. I appreciate your response!