Does preamp w/Power Supply need a good Power Cord?

Power cords have made a difference on the preamps I have owned with separate power supplies. In fact, I am auditioning a preamp with a separate power supply, and the designer purposely does not include a power cord because he believes the effects of aftermarket power cords can be significant, and he prefers that his customers experiment with them to suit their preferences.

There are some power cords at slightly above the $200 price level that can have a positive effect, IMO. For example, the Oyaide Tunami GPX, which can be found for slightly over $300 (or less used).

Yes, it will make a difference. You can get an Oyaide cord for 2-3 hundred, I use them. Also use Siltech, Spirit Sound has some demos beginning at $60 for 1M. I didn't use them for years myself, but it can make a big difference.

I good company to deal with is VH Audio..You can prety much have them built any flavor you want and at a reasonable price..Also easy to deal with..