Pre-amps with seperate power supplies .....

I have a Cary SLP05 preamp that has a separate power supply connected by an umbilical cord. I tried the RAL replacement and found the stock cord to be far superior. In all fairness, I probably didn't give the RAL umbilical enough time to break in but to my ears, it sounded horrible

Regarding the engineers at Classé knowing what they're doing, I recall a communication I had with the company many years ago. I had just purchased a new Classé amp that came with their $180.00 "Reference AC Linecord", a modest cable with a Schurter IEC plug on the amp end, and $3.00 yellow Eagle brand male plug on the wall end. Taken aback, I sent off a letter questioning their choice of an el-cheapo plug on a so-called "reference" cord. I received back a nice letter from a vice president at Classé stating that they had carefully auditioned a variety of AC plugs available at the time, both expensive and inexpensive, and found the modest Eagle plug to be the all-around best performer.

"As Grannyring astutely pointed out, there's is often room for improvement (sometimes significant) as an individual isn't hampered with the same cost constraints for their specific audio system."

Just what cost constraints do you think Classe Audio had when building the OP's $8,000 preamp? I always find it interesting, how many people think they know more than the specialty engineers designing high end audio equipment.

Gbart's post is a good illistration of how the cost of parts is not an indication of their worthyness in a specific application.

I know of at least one company that performed mods on many high end components. Their mods consisted of changing caps from the originals to much more expensive caps. This company destroyed the sound of some of the best equipment ever made. Thankfully they are now out of business. Hopefully never to return.

Grannyring said "Yes it would make a nice improvement" This is bad advice. He has no clue if it will make any improvement at all and there is a good chance it would sound worse at the OP's expense of course.

This appears to be the era of mod happy audiophiles. I can see modifying a Sony CD player if you are not concerned about getting the mod money back, but modifying the best equipment from the best companies is ludicrous. If you don't like it you should buy something else because it will eventually end up on the used market and I don't want to end up with it.

8000.00 USD for a component is no indication it uses the best parts available(it may or may not). The point to keep in mind is the option to upgrade is strictly an individual one.If you don`t believe in this concept then you don`t change parts,it really is that simple.A number of listeners have made substantial improvement it the sound quality of their audio components by installing better parts.Some have modified and have gotten worse results no doubt.Many have done modifications/upgrades and this resulted in noticeable improvements.It depends on the particular application.The basic /standard component can sound very good, yet this baseline level can be increased in many cases.
Regards,

Most manufactures of high priced equipment do not include a “named” audiophile approved power cord for the simple fact that buyers in the price bracket want the flexibility of choosing their own audiophile approved PC. It analogous to why hi-end speaker companies do not include speaker cables with their products.