On Thu, 6 Dec 2012 13:00:02 -0600, Darrall Dougherty
<darralld@hotmail.com> wrote:
> I show U22 as a NE5534 not a 5532?

Yes, sorry! That is a single. (As is, of course, the TL071 part
shown for U22 in the schematic.)

>  Also I already have the new RC4559's that I ordered to replace the
> ones already installed.
>  Will there be that much difference in the 5532's in place of the
> 4559's?

Yes. The 4559 is a piece of junk, don't put it in! If the old 4559's
are in working condition, there won't be any difference.

The NE5532 is the "audio champion" IC (33 years and counting!)
if we take into consideration price. Supposedly,
nothing can beat it that costs anywhere near as little,
on a combination of low distortion and noise performance.
IC's that perform better only provide diminishing
returns for more $$$.

One step-up from the NE5532 would be the LM4562 (developed only
quite recently!). It costs more.

For more info on op-amps, a fellow called NwAvGuy has some
web pages that are a nice start:

http://nwavguy.blogspot.ca/2011/08/op-amps-myths-facts.html
http://nwavguy.blogspot.ca/2011/08/op-amp-measurements.html

Excellent series on op amps by Douglas Self, in EE times:

Part 1: http://www.eetimes.com/design/audio-design/4216341/
Part 2: http://www.eetimes.com/design/audio-design/4217177/
Part 3: http://www.eetimes.com/design/audio-design/4218273/
Part 4: http://www.eetimes.com/design/audio-design/4219253/

The second page of part 3 has a discussion about the
NE5532 internals. 

 "As can be seen from Figure 4.20, the 5532 is almost
 distortion-free, even when driving the maximum 500 Ω load.
 The internal circuitry of the 5532 has never been publicly
 explained, but appears to consist of nested Miller loops
 that permit high levels of internal negative feedback."

>  Got the SA572 in today. Will install it when I get home.

Please jam on your S.S. channel before and after and
report.

Cheers ...