Do speaker wires matter

Sounds reasonable.  If the issue is the mirages, you might ask the repair person in Canada if it sounds like a foam repair issue or a driver issue, and feasibility of fixing that.

Basement is plenty large enough, though a 5' tall speaker in a 6' tall basement must be a sight.  I suspect you'd be better off with the speakers at least 3' away from the rear/side walls.  If you google the ancient reviews on the M1s, they may give you their opinion on the topic.  Or just experiment.

If the speaker works or can be made workable, an idea to save money is to buy used SS amp (of enough watts).  Just make sure it has been had capacitors replaced (if needed).  

Let us know how it turns out and how you like them.

I bet those speakers sound great!. I would like to hear them.

Efficiency: your speakers are very low efficiency. 83 db/1w/1m means they ONLY make 83db sound volume when given 1 watt measured 1 meter away, They need far more power than your Marantz, your Crown is plenty.

Happily, your Crown has gain controls on the back. like volume controls would be if on the front.

https://rocknrollvintage.com/listing/crown-power-base-2-power-amplifier/14177109

1. Hear your speakers with enough juice, your Crown Amp, your existing speaker cables.

a. First, turn Crown’s rear gain controls down to zero. spin them full turn several times to ’clean’ the internal contacts, then down to zero.
b. One Favorite CD with highs/mids/lows (see h below)
c. CD player direct to the Crown as a test.
d. Crown direct to speakers using existing speaker wire.
e. ON, hit play on CD player, wait till it’s into a track first.
f. Now, you can increase the rear gain controls bit by bit until you get a satisfactory volume.
g. turn the gain down low, some but not a lot of sound: listen to each driver to verify they are good.

h. DO NOT try another CD, without first turning the Crown’s rear gain controls back down. Some CD’s have significantly higher output that others.

2. TEST the MARANTZ as a Preamp to the Crown.

Marantz’s controls might be dirty, it might have an unknown problem, that is why it is the 2nd test, after you have determined the speakers are fine with the Crown.

a. Unplugged: turn all volume/tone/selector controls several full turns to ’clean’ them. Good enough for this test.
b. Crown Gain in the middle of it’s range to start
c. Marantz volume down.
d. Same CD
e. CD player to Marantz; Marantz to Crown, Crown to Speakers using same existing speaker wires.
f. Marantz Volume up half way IF not too loud.
g. Adjust Crown rear gain for good normal listening volume.
h. Marantz Volume, fully up too loud? Crown down. Not enough, Crown Up.

Note: Marantz controls might need further cleaning. If you hear static, or they seem inconsistent, if you know how, take the bottom off, front plate off, spray them/work them with contact cleaner/lubricant. Clean all the rear jacks while you are at it.

"Never even consider anything less than 92dB. Just cross it off your list. Too many fabulous sounding 95dB+ speakers out there to be killing yourself trying to solve a problem so easily avoided.  "                                                                                      Ok,so we cross off most of the Wilson line,the Vivid line,the Dynaudio line ,the Harbeth line, the Focal line ..on and on and on...thats the dumbest thing I've read on this site in a long time outside of your constant Tekton shill post..give us all a break with this ,please

Since it hasn't been mentioned yet the speakers being dipoles need to be placed fairly far out from the front wall in order to balance the sound.

I would try them 5'-10' out if possible playing around with toe in, maybe even zero toe in.

However, them being too close should not decrease the HF balance (quite the opposite I would think as most of the cancelation would be in the mid/lower frequencies).

DeKay

Everything matters.