Replace pwr cord w/IEC socket on vintage gear?

The procedure Rrog describes for orientation of two-prong plugs is good practice, although it may or may not make any difference with any given component in any given system. And in many cases the measurements being compared for the two orientations will be low and pretty much the same.

What the procedure does is to minimize low level leakage between the hot side of the ac line and chassis, which may particularly occur to some degree as a result of stray capacitance, and perhaps also degraded insulation, in the power transformer. Besides conceivably having effects on the sonics of the particular component, it could also result in extraneous low level ac hum and noise currents flowing through the return conductor of cables connecting that component to other components it may be driving, which would be indistinguishable by those components from signal voltages.

Regards,
-- Al

Rrog, you really think the engineers at Heathkit listened to the amp with different power cords and "voiced" it to their sonic preferences? You need to be careful when applying modern sensibilities to times gone by.

06-27-11: Gs5556
If that Heathkit is a tube amp without a protective cage, you do not want a grounding power cord for the same reason toasters and lamps are not furnished with three-prong plugs -- live parts exposed from damage have no bond to earth. Also, the grounded power cord can put the signal and chassis to the same ground, possibly causing sonic problems such as humming from ground looping. This really should be done by a pro.

It's solid state. In fact, here's an ad with specs. I hadn't mentioned it, but the captive cord is 2-prong, and it's quieter than the 3-prong amp I replaced it with. This thing can really dig out the low level detail.

06-27-11: Onhwy61
Rrog, you really think the engineers at Heathkit listened to the amp with different power cords and "voiced" it to their sonic preferences? You need to be careful when applying modern sensibilities to times gone by.

I was originally skeptical of Rrog's assertion, but why would this amp sound so *GOOD*? Here's this heavy, high current amp with a very modest 2-conductor cord. The amp sounds like the design was heavily prototyped, listened to and voiced carefully. It's fast but not edgy, resolving but not hyper-detailed, linear and accurate but not sterile.

The same store where I bought it has an '80s Precision Fidelity M-8 hybrid amp, This Stereophile review of an Electron Kinetics Eagle 2 indicates that the Precision Fidelity is the lusher and more musical amplifier.

Stltrains,
Units built in 60's 70's are very often have more advanced engineering than today's 'pure and minimalistic' designs. Having the fact that parameter tolerances for electronic and passive devices were much less precise, designing a well sounding unit was a great challenge.
These units might benefit from new parts equivalents but very tiny-likely you'll get desirable ROI from IEC/PC...