Passively bi-amping

I have 2 Pass Aleph 5 60 W stereo amps that I'm passivly bi-amping a pair of Nautalus 802's. Amp1 left channel powers the woofs, right channel the mids and tweets. Same with amp2. Is this worth doing or did I buy a second amp for no reason. I asked Nelson Pass if I could convert these to monoblocks, but he said no.
You did not buy a second amp for no reason. The Alephs are great amps. Possibly a bit shy of power for your B&W's.

Put one amp back up in stereo and listen for a while....then go back to the biamp configuration. You'll hear it.

I passively biamp my Aerial 20t's with Levinson 33H on the mids/tweeters and a 336 on the woofers. Either the 336 or the or the 33H's will do the job alone, however the pair make wonderful music.

Having said that, I know that your series B&W's are power hungry. If you have a McIntosh dealer nearby, you may want to take home a pair of the 501 monoblocks to try. I've demo'd these myself, and at the price point hard to beat.

Don't be an audiophile and change for the sake of change only however........always best to take it home and hear for yourself. Sometimes we get so the grass is always greener on the other side of the fence.......


One Aleph 5 is definitely not enough to power-up 802's and to be frankly not even enough both of them to open 'em up despite how great they are.
I disagree on the Aleph 5's. 802's are rated at 91 db and I've drivin them with one Aleph no problem. With both amps hooked up I reached 110db and man it was LOUD. I brought home a Ayre power amp home from my dealer. Don't know the model but it was 10 grand and weighed 95 pounds. I hooked it up to the 802's and at 200hz and below the Ayre was superior. Above that the Pass's blew the Ayre away both in sweetness, smothness, and all around sound quality. I took the Ayre back the next day. Yeah I wish my Alephs had more balls, but they are one of the best sounding amps I've ever heard. Not good for your electric bill, however.
I think you are definitely headed in the right direction by vertically bi-amping. I don't know what your system configuration is but if you can get your amps close to the speakers and use as short a speaker cable as possible will also show additional benefit. Almost as much improvement as going to bi-amping.

I also agree with the others about perhaps needing some more juice. I would be worried about the bottom end potentially clipping. Beyond that, there is a definite sonic improvement when your amps have lots of headroom and current to spare. I bet if you where to get a pair of 250.5's you would be quite surprised at the improvement in depth and clarity. That's not to say there is anything wrong with your Alephs, but just think what they could sound like if they were only driving the mids and highs. Your B&W's are similar to mine and Beemer's Aerials and we know how much these can open up with the addition of more quality power.

Another thing you could try is to keep the Alephs on the tops and get a more powerful Pass amp to run the bottom end. Yea, I know, I'm just spending your money. :)
If you go active, you can get some monster power(Sunfire 600 for example) for the bass and leave Aleph to do the rest of job.

B&W X-overs even on flagship models is not the best you could think of. Adding an electronic X-over(bypassing or removing the built-in one) will give you more flexibility to get from your speakers the best jewels without breaking the bank on a pair of x250's.
I hear active bi-amping is tricky and my personaly opinion is intergating subwoofers is almost impossible to get right.Plus my room is bass heavy. Could use a pair of 16" Tubetraps. I have a small room for such a large speaker and am able to acheive sufficent volume levels with the Aleph's. I don't have a lot of headroom. Turning the 802's any louder than my normal rock n' roll levels does cause bass clipping. Just have to keep an eye on things. I'm running 8ft Transparent speaker cables. Just wish I could have turned those 5's into monoblocks. Nelson Pass said no way. Don't have the scratch to be investing in any more equipment right now. Just be happy with what I have... Thanks for the feedback!
I do have some respect that these a under powered amps (Pass Aleph 5's) for the Nuatalus 802. I have a notch in my Aleph P. When turned all the way to it is plenty loud for this rock and roll animal. Bass is tight, no sign of distortion. However if I turn it up any more my amps run out of gas and the bass begins to clip. So I keep it under the notch and the sound is fantastic. Steely Dan's Aja is mind blowing. So is Gish by the Smashing Pumpkins. BTW I'm an analog enthusiest and also have a Pass Aleph Ono. Will take the Pepsi Challange against any CD player.