Denon PMA 980R For those that don't want to spend $$$$+$'s

You have quite a collection of amps there.

 As I can see, judging from the age of the Sansui, it may require a lot in funds to have that Sansui worked on. 
 The Acurus caught my eye. Have you considered teaming it with a tubed pre? I`ve teamed a tubed pre with an Adcom 5300 ( simular to the Acurus), and have gotten good results. 
 

'Loudness' is the stupidest name it could have been given, which is why it is misunderstood, then misused.

Leaving Loudness ON, at normal listening levels:

is the OPPOSITE of it's intended use, which is to BOOST Bass, for LOW LISTENING LEVELS, Progressive Boost with Diminishing Volume.

Because: our ability to hear bass relative to mids is progressively reduced at low volumes (equal at normal volumes).

https://en.wikipedia.org/wiki/Equal-loudness_contour

So, you are leaving it ON, finding it Bass Heavy, then turning the Bass Down. Creating and Solving A Problem.

I suggest, at normal listening volume, you turn Loudness OFF, and put your BASS Tone Control back to neutral. Then, use only the tone controls if you feel the frequency response needs a slight adjustment IN YOUR SPACE.

Afterall, the speaker maker's design for an imaginary average room, not your particular space. Vintage designs included L-Pads for frequency refinement, 1/2 attenuation the default, then boost for dead rooms or cut for live rooms, and your personal taste which is probably related to your hearing as well as your space.

Every loudness circuit I ever had tapered off when increasing the volume.  There is that.

The sound of the amp sounds fuller with the loudness switch on. And I will continue to use it that way.
Anyway.......

I have nothing in this stuff.

The Sansui will probably cost around $350 for a refurb. To me it’s worth it. And that will be by far the most I ever spent on any unit. New, or used!

Funny, no love for the great sounding 2040. The one I have has a lovely wood veneer case in a slightly darker honey color, with a voltage selector on the back. Great sounding unit that for some odd reason gets over looked. Like this 980R.

That $350 for a refurb, are you sure, that, is not just for the diagnostics and parts?
17 yrs. ago, my Sansui refurb was around $450.

And my local tech who became to old to work on gear was working on units and usually charging $300 like he did to service a Marantz 2500. About the same for a Yamaha CR 3020.

I will find out. 

Again, the PMA 980R is a fine performer.

I don't have to pay the Audiogon tax (Once in a while there is a good price on here)