Bi-amping Pass X.5 matches X.8 / XA.8 / X.5 / XA.5

Regarding vertical vs. horizontal biamping, see this post, which is written by a noted amplifier designer.

Also, while it might be possible to obtain reasonable results using four identical monoblocks, I agree with ZD that it would most likely make more sense to upgrade your speakers instead.

Finally, while I suspect that your 801 speakers have completely separate crossover circuits for their high and low frequency sections, before even considering biamping them you should confirm that with the manufacturer or a knowledgeable dealer. I believe that some speakers which provide separate input terminals for the highs and the lows do not keep the two sections completely separate electrically. Biamping such a speaker, especially with amps having balanced outputs such as these Pass models, could cause problems including even the possibility of damage.

Regards,
-- Al

upgrade to more powerful amp instead.

thank you all brothers' replies!!

If I don't add active crossover, then I don't need to bypass the built-in passive crossover in the speaker.

My present power amp is X1000.5, I think it is enough for many speaker.

Any more advice?

My present power amp is X1000.5, I think it is enough for many speaker.

Wow! That's for sure!

I'd just leave well enough alone, unless you feel the need to upgrade the speakers or something else in the system.

Even though all of the Pass amps are spec'd as having the same 26 db of gain, so you presumably wouldn't have a gain matching issue if you biamped, I suspect that biamping those amps with a different (and presumably lower powered) pair of Pass monoblocks stands a greater chance of adversely affecting sonics than of providing a benefit, as stated above and in the link I provided.

And adding two more X1000.5's, besides costing a great deal of money without necessarily providing any benefit, raises concerns about simply providing them all with enough AC power. You'd undoubtedly have to power each pair from different circuit breakers and different dedicated AC lines. Which in turn would create some risk of introducing ground loop issues into the system, although the fact that the components (and I presume their interconnections) are balanced would minimize that risk.

Sometimes the best thing to do is nothing. Or as the saying goes, "if it ain't broke, don't fix it."

Regards,
-- Al

Believer,

I can't really explain what the sound differences are because the results vary so much. Basically, it sounds like the speakers get broken up into different sounding sections. But, like I said, the results vary so much, the sound is completely system dependant. The best technical and listening analysis I've seen was in the publication The Audio Perfectionist Journal. Unfortunately, its no longer in production, but the first few issues were free, and that's where you'll find the info you are looking for on vertical biamping. The journal was issued on pdf so locating it may be possible. I don't know what happened to my copies, or I would just give them to you.

That said, have a look at this: http://vandersteen.com//media/files/Manuals/3asigmanual.pdf

Its an owners manual for Vandersteen speakers. In it, he goes over the various biamping options and can do a much better job of explaining it than me. The info can be applied to just about any speaker, not just Vandersteen. Although, Pass does sound wonderful with Vandersteen.