Amp to power surround channels for MUSIC ONLY

Here you go.   https://www.starkesound.com/detail.html?id=47  Check out the feedback on Starke on this forum.

Multi-channel amps aren't for "movies" or "music".  If they're good at one, they'll be good at the other.  Some multi-channel amps are better than others and both movies and music will sound better with a better amp/preamp/speakers. 

What's your budget?  Do you have space limitations?  Have you considered monoblocks?

Marantz MM7055
price will not break the bank
good quality for the price
Renowned brand
https://www.crutchfield.com/S-UN2QwUKhOh4/p_642MM7055/Marantz-MM7055.html

I have a couple Jaton Operetta AP5140A amplifiers (one 4 channel, the other 5) and find them to be excellent amplifiers for audio and video purposes.  I don't do surround sound and use the 4 channel to biamp custom speakers and the other is used for 2 channel purposes.  The first sounded so good I acquired a second as the used market prices are quite low, way too low given the sound quality.  There were a couple insightful reviews by Stereomojo and Hometheatersound but both have disappeared from the web.  I found an old sale ad with some quotes from those review which I'll paste below.  I am selling one and keeping the other as I'm in the long process of consolidating, going from 4 systems down to 2.  Check out my ad on USAudiomart under Jaton for more details on the sound of these very nice and affordable multi-channel amps.


Bill Schuchard StereoMojo "The Jaton AP2140A has a tight yet hefty
bottom end, a transparent articulate midrange, delicate highs, razor
sharp imaging, and is dead silent when there is nothing to play. It was
never bright or edgy and the bass emphasis came through nicely." "The
Jaton Operetta AP2140A is a great sounding amplifier and exceedingly
beautiful too."
Doug Blackburn HomeTheaterSound: "I’ve heard $1995
two-channel amps with less clarity and musical nature. The Operetta’s
midrange made it difficult to stop listening."
Finding out that the
Operetta amplifier could drive my loudspeakers to loud levels wasn't the
only surprise. This amp also sounded great - it is quite pleasing and
detailed. Vishay resistors, and Nichicon and Wima capacitors used
throughout. This is truly an amp that put a smile on your face. It will
please 99% of audiophiles. In both build and sound quality, this is
easily a $3K amp, listing for half of that.
Elegance, simplicity and
attention to detail rule its design. At its core sit two power modules
comprising National Semiconductors' LM3886 High-Performance Audio Power
Amplifier IC. Each module produces 70 watts into 8 ohms, modest by
modern standards, but like tube amps, these are sophisticated watts.
More importantly, the combined attention to circuit geometry and quality
components yields power with total harmonic distortion so low it left
National Semiconductors' own engineers double checking their
instruments.
All of this represents an elegantly radical approach to
circuitry so effective as to belie numbers. The proof is in the
listening: laser-like focus, precise separation, deft detail, and
sweeping soundstage.
The AP2140A is final assembled and tested in Jaton's headquarter Milpitas, California. It's clean and simple chassis is silver.
Specification:
Max Distribute Power: 140 Watts @ 4 Ohm,70 Watts @ 8 Ohm
Distribute Channel: 2 Channel
THD + N %: 0.01% @ 8 Ohm, 1 kHz, 70 Watts
Frequency Response: 16 Hz ~ 40 kHz, +/- 3 dB
Max Output Level: 23 Vrms
Input Sensitivity for 1W output: 84 mVrms
Dynamic Range: 150 dB Max Gain: 30 dB
Max Power Consumption: 950 watts

Check out d-sonic.com.  Their Class-D amps fly under the radar but get stellar reviews, and their sonic signature and price would seem to be in your ballpark. They also offer a 30-day in-home trial so easy and very little risk to try in your system.  Best of luck.