Confused and need help

I paired Maggie 1.7 with a Parasound hint Halo and the sound was phenomenal do I'm surprised that they may be your problem. Maybe an audio friend can bring an amp or pre so you can experiment.

+1 mofimadness
Location, location, location.

I completely agree with david_ten. Years go by, unless you have oodles of money, we make changes slowly. Our brains change slowly. Our ears change slowly. Our perception changes slowly. What we never imagined may all of a sudden be reality. All of a sudden a mismatch may become a match and the opposite. For instance, I have had some Roxy Music vinyl in my collection for a long time. Never cared for it. Tonight, I said let's give it a chance and loved it. Why? No clue. But sounded fabulous. Same system as last 5 years. Nobody ever takes into account aging as a major factor in this hobby. Why not? Every other aspect of society does. I can't imagine that I hear the music anything close to that which I did 20 years ago. Still love it the same. Actually, love it more. My brain now loves the sound, the variation, the skill, the talent, the time and artistry it took to create the recording. In the end however, it is still my ears sending the data through a neuro network of past memories to my brain and down to the pleasure receptors in my body which make the experience. Any hiccup in that chain results in alteration of perception and thus one's interpretation of the beauty.

What leads you to believe that the Maggies are "going faulty"?  Is it just because they've lost some sparkle?  If so, I'm with @mijostyn.  When was the last time you replaced the tubes in the LS17?  Good NOS tubes in a preamp can definitely bring back that sparkle.  Sometimes it happens so gradually you don't even realize it was gone until you replace the tubes.

2x parasound A21

I presume this means that you have used the two A21s in bridged mode. The manual for the A21 states as follows:

You should not connect a speaker with an impedance of less than 8 Ω to the A 21 when it is configured for bridged mono operation....

... We strongly recommend against using speakers rated at less than 8 Ω when bridging.

The Maggie 1.7 has a nominal impedance of 4 ohms. The Harbeth 30.2 has a nominal impedance of 6 ohms. Both speakers are therefore not good matches for bridged A21s.

Also, given that a single A21 operating in stereo mode is quite powerful (spec’d at 250 watts into 8 ohms and 400 watts into 4 ohms), and given that both speakers have sensitivities in the vicinity of 86 db or so, I would think it likely that a single A21 operated in stereo mode would provide enough power anyway.

And, finally, I see that the Harbeth has a "power handling" spec of 150 watts "programme," which is to say that a single A21 operating in stereo mode can most likely supply more than twice as much power into its 6 ohm impedance than the speaker can safely handle.

Regards,
-- Al