Vintage worth the time to explore?

If you get something from the 70's what might be helpful for you is most stuff had a "loudness" switch that will give you that warmth at low volumes. The marantz you mentioned probably has one.

Why not open back headphones like Grado's for when you want to play it loud? If you don't want to try that, And I also second:

1) Not buying anything older then 10 years. 

2) Looking for a system with a loudness button/control, or at the least tone controls.

the klipsch and elac speakers both sounded bright to my ears. mebbe if you got yourself an older yamaha amp with the variable loudness control? that would allow you to dial in a select amount of "warmth" without overdoing it. if you have money, to be on the safe side, you could get a pair of rega brio amps perhaps driven by a tube preamp, that would definitely warm up the sound. you don't want to even think about driving 2 pair with the brio. or you could try a brio or an old KLH receiver [warm sounding] with the elacs in front and a hafler circuit for the kg3 speakers on the rear [as they are mellower than the elacs, you don't want bright in the rears].

Consider moving to headphones.  The best modern examples provide awesome sound.  I bought electrostatic Stax back in 1995 for late night listening in a flat and they remain superb.

@deadhead1000   Rubbish that nothing over 10 years old is good.  There remain and always will remain some wonderful vintage amps that are iconic.  I have three. Audio Research SP10 (OK a pre-amp), Krell KSA50, their first product and their unbeatable KRS200, now pushing 40 years old, serviced and re-capped of course.

I find your handle very apt.  Stay with it.

I am somewhat biased since I own a recently refurbished Sony TA-N80ES. It's the same as the TA-N77ES but without the meters so it doesn't look as pretty. However, it sounds as good since the internals are the same. You should be able to find one for less than $1K refurbished (recapped, new transistors, etc.). If not a used one will run $400-$500 and another $300-$500 to be rebuilt. I own other great new amplifiers and am very happy with this Sony. I use it for a 2nd system with some Focal Kanta No.2 speakers and the sound is outstanding. It also has an attenuator on the amp that helps at low volume levels but I have never had a concern with that. If you want a receiver with all the pretty lights and meters I also would suggest a Sony, the STR-V6. I own one of those also and picked it up for $650 rebuilt and it is a fantastic receiver. It is connected to pair of "vintage" Mirage M760 speakers and tey are a great match. A pair of them can b pciked up for $500. I think they should go for a lot more as they sound better than many much more expensive speakers I recently auditioned. And 115WPC of the STR-V6 is good enough for most. Similar Pioneer, Marantz, Kenwood, Yamaha, and Sansui receivers are going for significantly more. Otherwise, if you can afford $2K then go with something more modern. There are a lot of great amps out there in that price bracket, both new and used.