TT Power Cord

OOPS Holly....I'm not with you on this one. In MY experience a proper power cord can be even more beneficial to the final sound than a switch to a better active component.

Power cords do make a difference. I even found that the power cord that serves the bias supply on my ESL speakers can make an audible difference. But the good news, IMO, is that cost is not a major factor. Cheap PCs can sound great. Expensive PCs can sound worse than factory-supplied PCs. I found that good speaker wire, if the gauge is high enough, usually make excellent PCs. Gauge is a major factor. Use 12-gauge from Home Depot or Loew's, if all else fails or on a budget, and if you know how to DIY a little. My theory, based on limited experimentation is that shielding and wire gauge are the major factors that distinguish good from bad, plus the amount of RFI and EMI in your own listening environment.

Lew, here is a case in point on using speaker wire. One of my audio buddies was caught up needing an extra power cord. Rather than go out to buy one he made it using a length of Kimber TC-8 speaker. That ended up sounding better than any other cord in his system, thus convincing him power cords can make a difference.

I think if your turntable has a mains regenerative power supply (the LP12 was possibly the first to use this principle) then it's likely that the power cord won't make a blind bit of difference.

Similarly any well designed power supply "should" be immune to the vagaries of the Mains but in practice the realities are somewhat different - and older classic gear can have more problems than recently manufactured stuff due to the fact that components have deteriorated over time.
This said, 110V supplies are a different story from 240V supplies such as we use here in the UK.

I remember, a while back, Rod Elliot of ESP Sound Systems doing an investigative study on this subject and seem to recall he found that braided "RFI suppressing" cables could have some benefit by reducing Mains noise but found no real evidence to support the claims of the others.
If you choose to access the following link, Rod is very passionate about de-bunking myths so you have been warned! :)

http://sound.westhost.com/cables-p4.htm#power

Mains cables with a ground sheath might well be worthwhile too for the above reason (important to note that won't have any effect on the embedded noise though) but I'm probably grasping at straws here. Exactly what form such interference might have on your listening pleasure is up for debate. With the advent of the possibility of transmitting RF data via the Mains the emphasis on well designed power supplies is increased.
Hope this helps.

No difference at all on the turntable....but what I thought was very interesting was that the entire audio spectrum was improved with audiophile power cables on my Vandersteen 5A speakers, even though only the woofers are powered...ODD....