The ups and downs of tube vs. SS...

I am a tube guy for quite while. I'm like to read articles concerning human hearing & perception of sound pressure levels and the effect of different levels of harmonic distortion on human hearing. Any suggestions?

There is precious little about this specific topic- for example GE's study is not online. But you don't need to read anything if you have the right test equipment- a sine/squarewave oscillator (as opposed to a generator), an amplifier of any kind, a speaker and a VU meter.

Set the oscillator to sine and drive the amp through the speaker. Put the VU meter in the circuit and set the level at 0VU. Then cover up the meter, and switch the oscillator to 'square' and set the level so it sounds at the same level as before. Uncover the meter, and you will see how much more sensitive our ears are to the higher ordered harmonics!

The tube amp sound less fatigue than SS and the impulse/dynamic is simply great. The only thing is that in the low end the energy is that strong as a SS.

If you want the bass energy in the tube amp to be right, the bass range of the speaker should be as high or higher than that of the mids and highs. Also, you will want to avoid 4 ohm speakers- with almost any output transformer, there is a loss of low frequency bandwidth driving from the 4 ohm tap as opposed to the 8 ohm tap (plus the amp will be smoother and more detailed driving higher impedances, which is true of **all** amplifiers). Also, keep your speaker cables short (under 7 feet!) and the connections at either end tight.

One obvious exception was when I put in my brother’s Bryston 7B-ST monoblocks and they buried the Vincent. A tad bright for my taste but the overall detail and the added bass was quite impressive.

@kalali Just think if you found it a tad bright now how you would feel after an extended audition? Even that extra detail can start to wear and just not with SS amps. I had a pushpull 45 amp on loan when Deja Vu was recapping my amp and I found it too detailed. All the details were making it hard to focus on the music.

I like tubes as well. Keep in mind however that not all tubes sound good. You can't just buy any tube amp/preamp and expect good sound. Not sure what your interests are but for others a good starting point is a single ended amplifier with appropriate speakers. Beware small tubes and beware tubes that produce lots and lots of power. Don' get more power then you absolutely need. Make those little tubes work a little bit. 

Two audio shows really shaped my opinions on tube gear.  One was a single ended symposium put on by Stereophile mag in the early-mid 90's in Philadelphia and it was the first time I heard SET gear.  That day I heard 845 amps, 300b, 211, and 2A3 amps from very well known designers.  They were all incredible sounding but the one that caught my ear the most was the least expensive and lowest powered amps the FI 2A3 monoblocks.  At 3 wpc, they were able to fill a 40 x 40 room with 104 db horn speakers.

Several years later, I went to another show in Central NJ sponsored by Vacuum Tube Valley magazine.  That day I heard great solid state systems, several digital class D amps w/tube preamps and many different tube amps both push pull and single ended.  I heard KT88, 6550, EL34, 6L6, 6BQ5, 6BG4 tubes in push pull and 300B, 2A3, 45, 50, 10 SET amps and again, to my ear, the best sounding was the lowest powered amps.

In PP, I thought the best was a moded Dynaco ST70 using 6BG4 in PP triode for 12 wpc along with an 18 wpc Dyna mk II which used 6BQ5 tubes; however, my overall favorite was the very low powered SET amps that were 2-3 wpc.  

Of course it's all about system synergy in every system you put together.  In the 5-7K range, I would tell you to spend about 2-2500 on a 45 or 2A3 amp and a nice pair of single driver Omegas and just save the rest of the money as I don't believe spending double will get that much better.  The 300B amps will get you double the power but replacing 300Bs can get very expensive.  

Keep us posted on what you end up with

@schubert Thanks for the reply which reinforces even more that there is no size fits all in the debate. The SP-T700's sound superb with rockier material, especially Americana, Alejandro Escovedo, Lucinda Williams, Steve Earle etc. No doubt ancillory equipment, Speakers, Power, Cables, matching etc. room, differ. This is why there is no definitive.

So to the OP, as you can see there are too many factors to rule out either topology, and as you've just seen musical preferences can be a big factor.

If finances allow get both!