upgrading to class D amp.....

Hello fellow music lovers.
I am looking to upgrade my amplifier to a class D or digital amplifier, due to the fact that my electric bill is getting out of hand, since I work from home three days a week, and equipment is on all day; being fairly ecologically conscious, i am tired of the my amp being so inefficient in energy use.
So I decided to take the plunge and look for class D or digital amp.
Why: energy efficient, size, and from what I have read, manufacturers have made leaps and bound in quality.
Budget: up to $ 2000 , used or new.
speakers : focal 836/91db efficient music: classic, blues, some rock.
Looking forward to opinions and advice.
Thank you.

what makes you think this is an "upgrade"?

Never mind Shakey's response. Over the years, I have used many different amps, Class A, AB, SET, and Class D most recently. I still use an SET 300B for that time when I feel the urge, but in order to not put too many hours on some very expensive output tubes, I use Class D Audio CDA 254 kit amps I built. The sound is smooth, detailed and capable of tremendous transient response.

I would have preferred the Hypex Core amps, but they're just too expensive for me.

A complete kit, such as I built, can be had for under $450, or, they have assembled amps for around $600 or so. They run very cool, sound great, and parts quality is high. The usual disclaimer applies here, I am not in any way affiliated with Class D Audio. Just a happy user.

What he said. I have a class d audio sds 470c and its price to performance is off the charts. Having said that the ncore amps are incredible. If I were in the market for new amps and had twice your budget I would jump on the ncore mono blocks listed on here for $1500 and pocket the rest. Best of luck with your decision.

I also recommend class d audio. The website pics dont do it justice - really great build quality inside and out and great balanced inputs if you use that. It sounded much better than the bel canto 7 i auditioned. There are other good class d amps but the prices are higher and its hard to beat the sq build and power you get with class d audio. 

Here I thought I`d be first in line to recommend the Class D Audio SDS 470C...Was wrong I see !
The SDS 470C has a nice sound stage wide and open, great detail too.
I had a Rogue ST90 that I really REALLY liked but my speakers could use more power so I got the Class D and was very pleasantly surprised !
They both have their merits and I can live with either but the added power of the 470C is nice to have @  300/600 watts.
Mine is silver with blue lights and looks nice !

It has a fairly hefty feel to it at 22Lbs no fly weight like some class d amps are.

I`ve said it before, for the money/performance ratio the 470C reminds me of the NAD 3020 I bought new back when to power my DCM Time Windows.

I say check out Red Dragon Audio's Class D amp offerings. I have the Red Dragon M1000 Mk1 monoblocks and I couldn't be happier. With my Ohm MicroWalsh Short SEs the M1000s made the music from them more lively than when I was using a Hafler 9505 or a Jolida 502P w/ Tung Sol KT150 power tubes. Even with a pair of ELAC Debut B6 speakers the music sounded more alive with the M1000 monos vs the other amps I have. The great thing too is the monoblocks only consume about 35 watts total vs the 300 watts the Jolida consumed.
I purchased the Wyred for Sound SX1000 mono block amps which we find to be a very compelling and solid choice. They have performed flawlessly for years. Fantastic liquid sound that I have only heard elsewhere in much more expensive equipment. We have their STP Preamp and DAC-2 DSD. Not the cheapest solution but IMHO a very compelling one even at double the present cost of admission. Their integrated amplifiers are really nice too. Hard to go wrong with any product they build.

Thank you for all the comments.

The next question is: does the preamp has to be of a certain kind, or can I use my vintage/rebuilt preamp/Sony TA77ES?

Thank you for all the info.