Who else is using old cables/interconnects, and is happy?

Just had an interesting experience w/elderly cables. It didn’t go well:

• I pulled 2 pairs of 5 ft long Monster Cable M1 speaker cables (late-’80s vintage) out of storage
• I decided to biwire my ATC SCM 12 Pro passive monitors w/them. I’d been meaning to try it, but only had one run/pair of AQ Type 4 cables, so had been stalling.
• To make this work, I had to get 8 spade-lug-to-banana adapters. I affixed them very tightly on 1/2 the spade lugs (which my particular amp/speaker set up requires)
• With a lot of pain & struggling (those old spade lugs just don’t want to work w/WBTs!), got it done. Let the cables cook for ~100 hrs.

The other day I fired up the ATCs. Frankly, it sounded like shit--not very similar to my usual system of AQ Type 4 cables + 2 pairs of no-name 4" 12 gauge jumpers for the ATCs. Suddenly there’s a broad glare in the upper mids & lower treble; also some grain in the treble. The bass (which is otherwise epic for a 2-way in these ATCs + JLAudio sub) suddenly goes less deep with less impact.

I suppose the 8 adapters could be at fault. But I tend to think that those old Monster Cables just aren’t as good as up-to-date Audioquest type 4s.

Just swapped them back to original cabling this morning, and that great sound is back.