As you found out Audphile 1 gave some good advise. I had Monster Interlink 400's in my system for many years and used Monster M1.4's speaker cables. Never gave it any more thought as I had read many articles that said cables made no difference and in my experience this was true.
Then after upgrading my components to a certain level I thought, what the hey, I'll buy some better cables just to make me feel better. I expected no improvement and to be honest was only upgrading for looks and bragging rites.
I started out with bargain cables replacing the Monster's with Outlaw PCA's. I figured that since there wasn't going to be any effect on the sound these were reasonably priced, big and cool looking and had locking connectors, which is a good thing.
To my surprise the sound changed when I rolled these cables in. Not drastically, but significantly. The bass was deeper with more detail, the highs actually seemed to be a little rolled off, everything just had a warmer sound. And, for the first time I realized what a big soundstage sounds like. The Monster were just dead flat in this regard.
This was the first time I had ever heard a difference and since I bought a Naim CDP and many Naim owners routinely recommend Chord cables I figured I'd experiment further.
I bought a pair of Chord Cobra IC's and ran them from CDP to preamp (Arcam AVP-700)(Still using the Outlaws from pre to power)and for the first time in the 30 years I've been into this hobby I heard more than a subtle difference between cables. Not snake oil or a psuedo effect of wanting to hear a difference, but a real difference.
To make a long story short, I continued down the slipperly slope of trying different combinations of cables until I found the one's that worked best with my system (Eichmann eXpress-6 series II. I love these cables).
IMO, IC's have a bigger effect on the sound than speaker cables, but then again I only tried one set of new speaker cables. They made the difference I was looking for and I was done (Alfa Core Goertz MI-2's) looking. Well I may try a pair of Eichmann's in the future if I can find a good used pair at a good price. But, just because I'm so happy with their IC's, not because I'm unhappy with the Goertz.
Anyhow, just for giggles I rolled the Monsters back in and the magic disappeared. I went between the Monsters and Goertz speakers cables and could hear no difference what so ever. Then I went back to the Eichman's and it was quite easy to hear the difference between the two speaker cables. The 400's were just not revealing enough.
I now feel like I've cheated myself for many years not believing cables made a difference.
But, I will also add that when rolling cables you have to remember it all starts at the source, which BTW, your Rega is pretty darned good.
If you continue to experiment (which you probably will now that you know there is a differnce, I recommend you buy used from this site and if you don't like the cable you wont lose much reselling. Also, you started with some pretty high dollar cables. It's not really about the price, it's about the synergy and how a specific cable works with your system.
BTW, which Klipsch do you own? I've owned the Cornwall's, Cornwall II's, and LaScalla's in the past. I tell you this because while horn speakers have many outstanding quality's that other speakers can't match, they also are not the best at presenting good depth and width to the sound stage. Not to knock your speakers, because I still miss mine, but this is just what I've experienced. And, I mention this only because this is one area where cables can make a huge difference, but maybe not so much with the horns.
You want to really hear your Klipsch sing put a good set of tubes up front. This will make a huge difference. Much more than you could ever hope to obtain from various cables. I had a nice set of class A mono blocks on mine for the longest time, and then a friend lent me a cheapo kit integrated tube amp (can't remember the brand, but I think it was dynaco, or something like that)and it was pure magic. Horns and tubes are a match made in heaven IMO.
