What makes the Bloom around instruments . . .

That definition of bloom by J. Gordon Holt correlates perfectly with Baranyi`s experience with his father`s violin comparisions.This presence of bloom is real and I`m aware of it when listening to live acoustic instruments be it a concert or friends practicing(piano,guitar,horns etc.)A good recording can capture some of this quaility and very good systems can reproduce it in your home. Based on the OP`s descrition aboveit seems the Pass amp has superior low level resolution/lower sound floor that`s allowing him to hear the natural bloom. The Spectron amp for what ever reason is`nt as resolved despite it`s other apparent advantages.

Rob (Rtn1) posted this to my system accidently and has asked me to move his thoughts to this post, if some of you don't know Rob, he is one of the ultimate audiophiles on Audiogon.

"Hi Chuck,

If one deconstructs a single note played on an acoustic instrument, such as piano/violin/cello, the concept of bloom can be better understood. As the musician transfers mechanical energy into the instrument, the body goes from rest to vibration. This transition is the leading edge of a note. The note will then reach its peak, and evolves depending upon how much energy was used. The evolution is due to individual parts of the instrument interacting with one another, to reinforce or cancel the vibration. This results in a complexity of sound and hue that is still part of the main vibration. Next, the instrument will come to rest, and the note will decay and fill the space of the hall.

The brain processes all this information and passes judgment as to whether it sounds ‘real’. If the leading edge or decay is too short, or if the evolution is too simplistic, the result is mechanical, analytical, fatiguing, etched. If it does not have the correct decay, the result is the dreaded black background. If the leading edge or trail is too long, the result is syrupy, hazy, boring. If these elements are correct, the sound is natural, and has a paradoxical detail. The detail is a sense of roundedness, texture, depth, and a floating sensation. Because the brain perceives the sound as natural and right, it has more agreeable detail compared to the analytic sound described above.

What is the basis of this natural sound? As others have surmised, part of it is recorded and part of it is introduced by components and cabling. I no longer understand the concepts of neutral, colored, distorted, etc. The goal is to have a sound that is real and right. Just as with a great dish, it takes many ingredients.

You are correct that the Pass XA.5 has this element. That is why I believe this amp is so special. I do think there are other ways there.

1) Tubed preamp ($$$$): Lots of good choices out there. Less if you wish to run balanced, which I recommend because of the Wadia. I believe this is the most important missing piece in your system. I also am convinced that at a volume level <90, the Wadia suffers from lack of detail and dynamics.
2) Jade Audio Cables ($$): JD uses fine gauge, multistranded gold and silver wire to create this bloom. His cables are all about that natural bloom, and I have yet to hear a IC or SC that does this better. His cables are close to adding a tubed preamp, with none of that syrupy mid, rolled treble, or muted bass.
3) NVS Sound Power Cables ($$$): Nathan is using some very special wire and techniques to create this decay and sense of space. You should speak with him and describe what you need.
4) HiFi Tuning Gold Fuses ($): I tried the silver fuses, and they were mechanical. The gold ones are just right in my system.

Best of luck on your new obsession. This element has been my obsession for the past year."

Chuck

Thanks to everyone! Now my heads spinning trying to explain my thoughts about what the Bloom is to me.

I have a soundstage that is detailed, wide, deep and layered. I think that the Bloom that I'm wanting is the glow or highlighting around each instrument. It does seem to be highlighted by a blacker void around it, which brings out even more minute aspects of the tones, making it more realistic sounding.

It sounds like you've all got me seeing that the most important ingredient is lowering the background even more to let the micro pieces show themselves first. Then maybe enhancing it further if I need to with either mods or upgrades.

Thanks again to everyone!
Chuck

Krell_man do you live any where near NYC? Let me know.

Did you ever think that the "digital" Spectron amps, although very clean and detailed, are just not able to recreate the natural bloom of an instrument because of their digital nature? I know the good digital amps I've heard, and I've heard good and bad, can sound very nice, but they don't sound natural to me either,and I doubt that I could live with one for very long. Too analytical for my taste's, though they seem to be getting better as manufacturers improve the technology.

I always attributed good bloom to good room treatments and speaker placement. But since the only thing you changed was the amp then I assume your room is set up to allow the bllom to radiate, if it is there. It could also be partially a simple cable mismatch with the Spectron, or a power conditioning problem. But I suspect that it's more in the nature of the 2 amps.