amp (or receiver) recommendation for Polk Audio RTi A7 floorstanding speakers


I started off building a 7.1 home theater system. Based on advice received here, I changed my plans. I'm re-purposing some of my components to a dedicated music system in another room. I would like some advice on this music system. (I'm keeping the home theater system in the smaller room and using smaller speakers with it.)

I am looking for a music system that will give me smooth, sweet, soft, silky treble with instruments like the Indian sitar or sarangi. These instruments can be challenging. I hope the system also has clarity and detail and enough punch for alternative rock in a large room.

I have two possibilities for listening location. One room is 18 feet x 22 feet with a tile floor, floor to ceiling windows on back wall and 8 foot ceiling. The front wall has a book case.

The other possible room is about 25 feet x 40 feet with a vaulted ceiling (approx 16+ feet at center). Back wall is also mostly glass. Flooring will be wood soon, but for now it is carpet. Neither room has curtains (or any window treatments) over the windows.

My old room was 11.5 feet x 11.5 feet and these speakers were too much for that small space (along with a large TV).

Let's assume I can arrange either new room so that my listening position and the speaker placement closely conforms to the "golden ratio" (http://www.ecoustics.com/articles/stereo-speaker-placement-optimum-sound/).

Here are the components I already own and would like to use:

  • pair of Polk Audio RTi A7 floorstanding speakers (8 ohms) - Sensitivity (1 watt @ 1 meter): 89 dB. Recommended Amp Power Per Channel: 20 watts → 300 watts
  • pair of Polk Audio RTi A5 floorstanding speakers (8 ohms) - Sensitivity (1 watt @ 1 meter): 90 dB. Recommended Amp Power Per Channel: 20 watts → 250 watts
  • Klipsch RP-250C Center Channel Speaker (probably won't use)
  • Klipsch R-112SW Subwoofer 600 W, powered
  • LG UP875 4K BLU-RAY PLAYER (plays audio CDs) (features HDMI, USB, and optical digital audio output)
  • computer with Asus X99 Deluxe II motherboard featuring Crystal Sound 3 audio (https://www.asus.com/us/Motherboards/X99-DELUXE-II/) (features USB, HDMI or optical S/SPIF output)
  • Focusrite Scarlett 6i6 USB audio interface (if needed) (https://us.focusrite.com/usb-audio-interfaces/scarlett-6i6)

Music will be played from my computer or the LG UP875 disc player.

What I have in mind is a 2.1 system with TWO pairs of front speakers (4 speakers total). I tried a dual front speaker setup briefly and I liked it, although I understand it is unconventional. But I have the speakers and I would like to try using them all. (If that is a really bad idea, even in a larger room, I'll give up on it.)

Also, I am curious to try bi-amp'ing and the speakers support it. If I use dual front speakers and bi-amp them 8 powered channels are required.

In a smaller room, I would not need a subwoofer with these front speakers. I don't know how that will turn out in a larger room. I don't listen to bass boosted music. But I assume I'll need a subwoofer. I assume I will not use the center channel speaker at all. I can return it.

Here's what I anticipate I'll need:

  • something with an amplifier
  • something with a sub out for the subwoofer
  • something to connect everything together (and, I guess, let me choose between the disc player and computer as sources)

What I do *not* need from the new components:
  • analog input sources
  • streaming, WiFi or networking (other than what I do with the computer)
  • home theater features or video support
My budget is about $1000, although I have some flexibility. But I only have about $2300 invested in the other components (not counting the center speaker, which I won't use, or the computer which is multi-purpose). So it doesn't seem to make sense to spend a whole lot more.

I am new to audio and home theater. I'm just learning now and I want to gain some experience before I increase my budget too much. Later, if I purchase much more expensive speakers, I'll get a more expensive preamp / amp combo. In my (limited) understanding the heart of an audio system -- where the money should be spent -- is the speakers and the amp. But with my most expensive speakers (the A7's) being $600/pair, it seems unreasonable to spend more than $1000 on a preamp+amp / integrated amp / stereo receiver (whichever is recommended) for this setup. If my logic is wrong, I guess I could be talked into increasing the budget to $2000 or so.
lowoverdrive
For a very sweet top end, Harbeth is probably the brand to go for. They are expensive, but fortunately not fussy about amplification. Their designer Alan Shaw argues that any properly designed and powerful enough mainstream amplifier will do, and for the forthcoming Bristol Audio show he intends to demonstrate their P3ESR mini monitor with a Yamaha AS 701. For his bigger speakers in a big room he recommends a lot more power (at the lowest price per watt).
See here for their M30.1, the smallest that I think you might use comfortably in the smallest of your two potential music rooms: http://www.theabsolutesound.com/articles/harbeth-monitor-301-loudspeaker/
Or here for their M40.2, their biggest and most expensive: http://www.theabsolutesound.com/articles/harbeth-monitor-402-loudspeaker/
Honestly, I think bi-amping speakers like those Polk is a total waste. I've got a friend with a pile of RTi stuff and it's nowhere near refined enough to warrant bi-amping. He comes over and drools on my Focals and FW F5 just dreaming his stuff sounded half that good. New speakers first and foremost. 
I know you liked the sound previously with two front speakers. Once you get your system set up, please try using only the large towers with a compatible amp.
A speaker is designed to stand alone with air on all sides. With a 2nd speaker next to it, the resonance of the cabinet and the function of the port is affected. Also, there will be phase and timing differences in the dispersion and arrival times of sound waves in the room.

Multiple speaker stacks are used in PA systems, not when you are seeking realistic high quality imaging.
Something like the Peachtree Audio Nova 220 SE integrated amp would fill the bill.  There are 2 for sale on this site right now and you should be able to buy it for your $1K budget.  You are going to need a lot of power to drive those speakers in either of those rooms (IMO, the bigger room is WAY too big for anything other than a megabuck amp AND more sensitive speakers...speaker output, i.e., apparent volume, drops off exponentially with distance) even if you do use subs to take the low frequency load off the main amp.  Which I strongly recommend.  It has multiple digital inputs, one analog input, pre-amp out to drive a sub, 220 wpc and pretty highly reviewed by the audiophile press. There is also a Belles integrated available at the same cost but it has 1/2 the power and I believe it has only analog inputs (not sure about that last bit).  No relation to either seller.