My turn.

[Alonzo]

Not a problem, we were all there at one point or another.  For the basics, always respect the research that has been done before you so if you keep to the specs of the original you shouldn't break anything.  So the VDC should be no lower than the part you are replacing.  If your going for something like the beeswax Jupiter's, make sure the temp rating works with the environment of the amp.  For a basic comparison chart of caps, check out Humble Homemade HiFi, they've done a comparison of a ton of caps and rate them.  But you have to take that with a grain of salt too because it's all system dependent and your ears are part of the system.  (my rant, others may disagree)
There's also a fandom for bypassing basic caps with others to improve the sound.  If you read some of the other "cap replacement" threads you'll see that some people like bypasses, some people think you should just get a good cap in the first place.
There's also some other posts on uF values, with and without the math to work thru.
So basically, pick a comfortable dollar value, find something comparable to the cap you are replacing and try it out.  Remember to give it time for "break in" (another debated topic)

[bAd]

Greatly appreciated.

[ALL212]

I used Clarity Cap MR series - about $100 each.  My other go to are SoniCaps - those about $22 each.  I really like the Clarity Caps for this level of device.

[mcandmar]

Not sure where the suggestion for 15uf came from as the stock caps are 10uf if i am not mistaken.  I am sure you could go a lot smaller in value than that without issue.

[Paul Birkeland]

I sure would be trying a different source before running off and buying different coupling capacitors. 

Your description sounds a lot like my opinion of most pro audio gear, and those common flaws would be easily masked by a higher distortion/lower quality amplifier (like the Crack).

Trying a different source doesn't mean spending any money, borrow one or find something interesting on Craigslist and haul your Mainline over to have a listen.

-PB

[bAd]

Great response!  It makes sense.  I also own HDVA600 which I don't have anything good to say about.  (Probably for the same reason.)  I don't hear any depth, clarity, and separation in it as others with nice DAC's can't stop raving about.  As of right now as far as I can hear HDVA600 is really well balanced in the sound spectrum, but also really blurry. So there we go!  I'm saving money for a DAC.  Any reasonable suggestions?
Thank you.

[Strikkflypilot]

From an audiologist point of view, the hearing potential of the listener is of course also important.
For different reasons, the tolerance levels in certain frequencies may be lower for some listeners than for others.

[bAd]

Yes sir. Well said. That's why I'm a big fan of EQing NOT the music material, but headphones to compensate for all the resonance taking an effect in my ear. What sounds good to me may not sound good to someone else. Every ear is different.
Cheers!