I'd put the right connector on my cable.  All my amp cables are 10awg which is good for 20 amp+ but I put 15 amp iec connectors on them to match the amp.

Most power cables come with the right adapter on it. where did you get one with a larger connector?

Jerry

I have 2 Shunyata Copperhead cables I use with the adaptor.  One uses the VooDoo and the other is the Pangea.  I hear absolutely no difference.  At the time, the Pangea was much cheaper than the VooDoo.

I’m with @carlsbad2 on this.  Terminate the cable with a 15A connector.

I compared the cheap ones with some $89 Voo-doos, the difference is enormous in favor of these. It was important to give them a long Burn-in period to obtain better results.
Finally, I changed my 15A cables to Transparent XL 20A IEC-19.

Hey, It takes 10 min to change out the IEC. If you feel you are degrading the resale value then just buy the Amazon adapter. It goes on very secure. 

I have a power conditioner that only accepts 20a plug on the iec end.  I would like to try some of my 15a cables but don't want to pay to get them changed and don't like the sound. I have one that would cost $150 to re-terminate.  This power conditioner is the only piece of equipment that requires  20a iec.

I am looking at their 15a to 20a adapter.

I have both adapters from Voodoo. Not sure if my mind playing tricks on me but the lesser $89 did perform less than the $200 one.
Note 1: I only left the $89 in system for few days and couldn’t bare it so it’s has never returned to my system. I seem to be more happy with the more expensive $200 one. Both have life time warranty. The $200 one I bought from eBay certainly went bad on me. I called Voodoo in hope they could repair- they sent out a new one the next day all free of charge. 

Note 2: same power cord, I later swapped out with new 20A plug and I thought music flows even better.

@nasaman 

Both have life time warranty.

I was thinking why would an adapter even need a warranty?  And then you needed it.

Yup. Same exact thought but when I checked out the pins with my ohm meter, 1 of them opened.

All Voodoo products (interconnects and pwr cords) have life time Warranty

I also want to add that Brian Tucker, a USA distributor for Puritan Audio was super nice and helpful. He helped me troubled shoot my Puritan 156 and also added that if my Puritan died and not working? it would be the very first that he has a problem with.