Power Cord with a 20 amp female and 15 amp male ?

I would use a cable manufactured by Dave.

Sadly almost all aftermarket power cord manufacturers make power cords with a 20 amp IEC female connector with a NEMA 125V 5-15P 15 amp plug on the other end. And what's worst the power cord might even be UL listed.

The company that makes the power conditioner makes such a power cord.
Link

Silver Circle 5.0SE power conditioner

Not sure what good a 5Kva isolation transformer connected to a 120V 20 amp branch circuit let alone a 120V 15 amp branch circuit.

A 5Kva, 5000Va, transformer is good for 41.67 amps continuous FLA at 120Vac.

Available Power in = available power out - core loses.

In other words continuous available power for a 20 amp dedicated 120V branch circuit is 120V X 20 amps = 2400Va.

For a 120V 15 amp dedicated branch the continuous available power is 120V X 15 amps = 1800Va.

If the unit will be plugged into a 120V 15 amp convenience outlet branch circuit that is sharing other loads there is the possibility when the unit is first powered on it may trip the 15 amp branch circuit breaker at the electrical panel due to inrush current.
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Pangea makes an adapter that 'might' be what you are looking for?

Pangea makes an adapter that 'might' be what you are looking for?

Try The Cable Company. They're the largest cable retailer and should have what you are looking for.

....and Dave is who ????

Dave's not here.

Shunyata will do this for you. Just call the Cable Company.

08-11-15: Jea48
Not sure what good a 5Kva isolation transformer connected to a 120V 20 amp branch circuit let alone a 120V 15 amp branch circuit is supposed to do....

... If the unit will be plugged into a 120V 15 amp convenience outlet branch circuit that has other loads connected to it there is the possibility when the unit is first powered on it may trip the 15 amp branch circuit breaker at the electrical panel due to inrush current.

Jim, I'm not entirely certain but I believe the more than 2:1 margin between xfmr rating and max VA may actually work in the direction of minimizing the possibility of inrush current issues. The reason being that it would reduce the possibility of core saturation at turn-on. Core saturation, if it were to occur, would tend to nullify the winding inductance, and hence the impedance it would present to abrupt changes in current.

Garebear, presumably the Dave who was referred to is Dave Stanard, proprietor of Silver Circle Audio.

Regards,
-- Al

Transparent will do this as well.

I had Kimber build a 20A PK10 power cord for use with my Bryston AVR20 isolation transformer. I was surprised when it arrived with a Wattgate 330i type male end. My shop inquired with them about it and we were told that the cord was good for 20A usage. As long as the connector is rated for 20A, which in my case the 330i presumably is, the orientation of the tangs is not important. It's been in the system for about three months and is working fine.

My shop inquired with them about it and we were told that the cord was good for 20A usage. As long as the connector is rated for 20A, which in my case the 330i presumably is, the orientation of the tangs is not important.
10-14-15: Reynolds853

Example of the Wattgate 330i plug.

You were told wrong. The 330i is a 5-15P 15 amp rated plug....
NEMA safety standards for plug and receptacles are supposed to prevent the general public from being able to use the wrong voltage, or amperage, plug or receptacle to feed an appliance or a piece of equipment.

Per NEMA, UL, CSA, NEC, ect, the maximum allowed continuous connected FLA load of an appliance or a piece of equipment with a NEMA 5-15P 15 amp rated plug is 12 amps....
For a NEMA 5-20P 20 amp rated plug, 16 amps.

What the PK10 power cord with a 15 amp plug in the eyes of a recognized third party testing laboratory is a 15 amp rated power cord. The wire could be as big as a house but because of the plug configuration it is rated to be used on equipment with an FLA of 12 amps or less. And that is the problem with IEC connectors..... They are not what is called in the electrical industry as being idiot proof.

Good example are consumer portable space heaters and portable vacuum cleaners. Because most of the receptacles in our homes are 15 amp, connected to 15 amp branch circuits, if manufactures of portable space heaters and vacuum cleaners want to sell their products to the general public they need to use the a standard NEMA 15 amp plug. In doing so the continuous FLA of their equipment must be rated for 12 amps or less. That is if the equipment is safety Listed. Other wise it could be a fire hazard.
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Here's a bit of advice from someone who had tied a few power conditioners and a lot of power cords. The wrong power cord on a conditioner (which already alters the sound sometimes in a bad way) just goes too far in even changing speed and the life of the music. Especially when using good power cords from the conditioner. Make sure you aren't trying to compensate for system coloration with a conditioner when upgrade cables are in order. If you use a conditioner first then try to upgrade cables it's harder to tell what's going on.

Aintitgr8, that is very good advice indeed !

Triode Wire Labs, VH Audio...