Best Amp for Timbre, Depth and Spatial Resolution?

I am glad we have a discussion about audio again :)

Ok here is the second part of my write-up:

To realize why room correction softwares yields a superior soundstage it is important to realize that:

On one hand, one does not want to excite room modes as that will lead to nasty bass resonances and nulls. Therefore, it is desirable to NOT place the speakers symmetrically with respect of the walls in the room. This is exactly what Wolf_Gargia has pointed out. However, on the other hand, to achieve a perfect soundstage, one has to place the speakers symmetrically with respect to room walls as one wants identical acoustic paths. Consequently, one is always faced with a dilemma to optimize the speaker position for the best bass response or for the best stereo image. (In the case of small speakers with limited bass output the situation is most often not critical and acceptable compromises can always be found. In the case of large speakers with healthy bass, however, this becomes problematic. In this second case, one's priority is always to optimize the position of the speaker to obtain the best bass response. Thus, having nor a "perfect" soundstage.)

Now, the reason Bo obtains a much better soundstage is because room correction systems, can actually optimize both issues mentioned above at the same time. Moreover, if one used two speakers and a subwoofer, the contradictory issue above is completely removed by sending all low frequencies to a separate subwoofer which can be placed anywhere in the room (e.g. the place that gives the best bass response). This is why Bo is crossing over his sub very high, I believe at 140 Hz or so. This in turn explains why REL subs are too slow for him - they are not design to play that high. Please also note that a similar approach is used also by Lyngdorf in their room correction procedure, i.e. in Lyngdorf system the subwoofers are crossed over at even higher frequencies, i.e. 250 - 300 Hz or os.

The opinions are very divided here. Some argue that when crossing over the sub so high one can get rig of most room resonances, while other argue that it is not a good thing as our ear will be able to detect the source of the low frequency. Since I simply do not know what is the right thing to do, I will just give both camps the benefit of the doubt and acknowledge that room correction has come a very long way.

I too use a room correction system, not a home-cinema Onkyo like Bo, but an Accuphase stereo unit that can not account for a sub and which most likely is not as advanced as the Audyssey Pro. While I had very few lab rats in my room (as I am not in the business like Bo) I too can attest that stereo purists (even very experienced ones), are extremely impress by the three dimensional and holographic stage obtained when using such softwares. This happens because they are not much aware of these "home theater tricks". They know they have done their homework at home and positioned the speakers correctly and in some cases even added acoustic treatments. However, they simply do not know/understand how crucial it is to have almost identical phases and frequency responses at the listing position from the two speakers and/or how easy is to perturb these parameters.

(I find this perfectly normal since as humans, i.e. we are not waves, we have very little feeling for phenomena like interference. I am a physicist and I have spent countless hour in the lab aligning and tuning lasers. While I am fully aware of how crucial is to have an exact phase and/or wavelength in the lab, I too was very surprised the first time I have heard a truly holographic sound stage - not surprizing given the fact that in the lab I was using an oscilloscope, i.e. not my ears.)

What I have found very interesting and funny at the same time is the fact that home-theater geeks, are much less impressed, if at all, to hear this holographic soundstage. They typically comment something like "big deal … you have used something like Audyssey XT with your Accuphase system to obtain a three dimensional static image… my home cinema system makes things flying around me ". The first time I was told this I was perplex. My friend's answer took me totally by surprise. . :)

Regarding timber and room correction software:

My experience (with the unit that I use) is that to obtain an accurate timber when using room correction softwares, it is crucial to use the room correction software as little as possible. That is, one has to place the speakers (and subwoofer if applicable) in the best place possible, so only minimal corrections need to be applied. It is very easy to screw things up, and suck the life out of the music, especially if one is naive enough to think that you can place the speakers randomly in the room and let the software take care of everything else. (Most likely, I am not the only one here who has heard room correction softwares sucking the life out of the music while at the same time giving a perfect holographic soundstage.)

Now, it seems to me that Bo here, is one of those home-theater-tech-guys that sets up Audyssey based systems in people's home - a rather common thing in the home theater business, I might add. Therefore, he most likely knows what he is doing and as a result most of the time he
obtains a satisfying timber along with the holographic soundstage. I am very sure that timber accuracy is the reason why Bo insists that Pass Labs amps are so important in his set up - he needs to inject some life into an otherwise rather sterile/cold system (Onkyo and Monitor Audio Platinum) - my opinion of course. Therefore, knowing the reactions of my few audiophile friends to the 3D soundstage in my room, I have no doubt that Bo is impressing many of his clients big time with his demos.

However, people should realize two important things. First, most recordings (and especially the rock ones) do not contain much, if any, holographic three-dimentional information encoded on them. (I am talking about 3D not 2D soundstage). Therefore, while impressive in a demo (with specific songs), such systems will most likely not be as impressive when playing one's entire album collection. Some specific recordings will certainly sound very impressive but only a very small percent of one's collection. Secondly, one can not conclude that because of its significantly superior soundstage a system with room correction is clearly superior to a system without room correction.

As it turns out (see the quotes below), this is exactly what Bo is doing when drawing conclusions about many of the components he is trashing. This should be very clear from his post above:

6 months ago I listend to the latest 800D. The image was almost flat at the show. I was at the same show and I had a very deep and wide stage with the same music.

Similarly, in the thread:

Why are subwoofers so polarizing?

he writes:

What I do is I send clients to shops were they sell Velodyne. It is not my responsibility how they do there demo. This is a very easy way to convince. I never heard a demo of a Velodyne at a show that I was thrilled. I Always have my own cd's with me.

I let you draw your own conclusions.

Who was the bullet headed reviewer dude at Stereo Review way back when who swore up and down that amps that measure about the same sound about the same? Lots of laughs!

Don't forget the initial question of this topic! Give some brand names and stop arguing to know who has the bigger P...
Everything you say about optimization is right. Using an Audissey pro is the easiest way.
Amps are of course too different to be affirmative on the final result and you also need to try them on your specific speakers to get the perfect synergy.
So the question is too twisted to be answered : Best amp do not really exist without the rest of the system!

Geoffkit,

It was Julian Hirsch (RIP), a highly respected reviewer for decades. He did not say that amps (or any other compnents) that measure the same, sound the same. What he did say was that if the measurements of two amps were very good and close to each other, both will sound very good and then it is a matter of personal taste which one prefers. In other words, he established the objective, so the buyer could apply his/her subjective taste. Most reviewers today only focus on the subjective.

Neal