Horizontal bi-amping for 3a Signatures

I have a pair of PS Audio HCA-2 amps that I am currently using in horizontal bi-amping for my current speakers resulting in an improved sound. I also have a pair of Vandy 2wqs. I have almost certainly decided to purchase a pair of Vandersteen 3a Signatures. I am almost certain I read in one of the Audio Perfectionist Journals by Richard Hardesty (which I dont have access to the copy that made the reference to which I will refer)that audio nirvan is attained by employing horizonatal bi-amping for the 3a Sigs.

I just read the 3a Signature manual and it recommends Horizontal bi-amping. As i read further in the manual, even though it doesnt say not to do horizontal bi-amping specifically, it only gives wiring diagrams for bi wiring and vertical bi-amping. Vandersteen goes further to say, the improvement for bi amping is minimal and suggest the "BEST" thing to do would be to buy the best single amp your budget can afford and bi-wire.

My problem is that PS audio does not recommend to use the HCA 2 in the mono block configuration.

Can anyone clear this up please?
Signed confused owner of apair of HCA-2s.
If by horizontal bi-amping you mean one amp for the tweeters and the other amp for the mids/bass then you're good to a point. You also need an active XO to adjust for volume and maybe even cross over point. See Behringer CX3410 or more complex DCX 2496
I tried both a vertical and horizontal bi-amp with my 3a's and ultimately went to one more powerful higher quality amp. I first used 2 Parasound A23's and now use a Parasound A21. I do not know if it was psychological or not, but when running in a horizontal biamp configuration things just seemed a little disconnected that seemed to disappear when vertically biamped. Today, I am much happier with the 1 larger amp and it sounds much more whole and balanced. On a side note, in my experience the 3a's respond very well with a lot of power even with the 2wqs.
Just to clarify, I do mean one identical amp powering the mids and tweets, and one amp powering the subs.
update: I sent an email to Richard Hardesty (audioperfectionist.com) and he graciously responded. He indicates that due to technical condsiderations, he no longer is recommending horizontal biamping with the vandy 3a sigs.

I also posted the same question on the Vandersteen website and Richard Vandersteen confirmed that horizonatal biamping was not recommended.

Vertical bi-amping works just fine and there are some considerations that make it appropriate. For example, If you already have one good amp and can get a match at a good price.
I used a pair of Counterpoint SA-220s to vertically bi-amp my 3A signatures for years. It sounded amazing.
I noticed Swampwalker and Nickword posts refer to "vertical biamping" For clarification, I assume that you are using a mono block for each channel right?
Vertical biamping in my case meant one stereo amp per speaker with one channel driving the high end and one channel driving the low end.
I'm currently running a pair of McCormack DNA-1 DLX Rev A's vertically driving my Vandersteen 3A Sig and they sound incredible. I use a McCormack TLC-1 DLX with the passive output driving the high/mid section and the buffered output driving the low section. With this set up I get the best of both world passive and active. At one point I was driving these with a pair of DNA-1 monoblocks but I found I get better resolution and detail with the vertical biamp and the passive preamp. I'm willing to bet if you experiment a little you will find the vertical biamping will work better overall.
I'm curious as to exactly why horizontal bi-amp is discouraged by Vandersteen and Hardesty. Other than extra cable lengths, the reasons are not obvious to me.
Unsound I was worried about this subject myself when I was thinking about bi-amping my 3A's. After reading through the Q&A section on Vandersteens web site he states that "I do not recommend bi-amping especially solid state because the channel driving see's only caps which can cause oscillations and potential expensive speaker damage (Non Warranty)". That was enough to scare me but I had also read a few time where Steve McCormack recommended bi-amping in certain situation. So I emailed him to ask and he said he hadn't had any problem so I thought I would give it a try and haven't had any problems. So now the Question is DO YOU FEEL LUCKY WELL DO YA (LOL).......I'm still nervous but love the sound I'm getting.
Nickword is correct in terms of terminology. Vertical bi-amping is using one stereo amp per channel and wiring one channel of that amp to the tweeter terminal and one to the woof/mid terminal. Obviously, the amps have to be identical in either case (unless you have an active x-over and go horizontal). Two DNA Rev A amps is a great set up with 3A sigs, but if you have the 2WQ sub(s), then I would recommend the 0.5 and spend the extra $ to go to an A+/Platinum upgrade. The idea of vertical bi-amping is to reduce cross talk and increase separation. If you are using one monoblock per channel, you cannot bi-amp, as you only have 2 channels of amplification total. Of course to bi-amp, you need 2 pairs of speaker cables.
One of the advantages of vertical biamping with stereo amps is that the power supply of the amp is only supplying the current needed for one channel of bass.

I have owned some of the best tube and SS amps made and with everyone one of them the bass sounded significantly better when they were used to vertically biamp.