My Krell amp had a captive power cord. I cut it off about one inch from where it exits the amp's rear panel, wired in a Furutech FI-33 Gold 20amp IEC (see VHAudio.com for a good selection of IEC choices) and used a dremel tool to enlarge the hole in the rear panel to fit the IEC. It took a couple of hours from start to finish. The IEC mod looks OEM now and I can change out power cords (with 20A plugs of course) at will.
An easier but less tidy method is to cut the captive power cord 2-3 inches out from where it exits the amp's rear panel and create a 'pigtail' using the IEC of your choice and a thorough application of heat shrink tubing or electrical tape, making sure to completely cover and insulate all metal surfaces for safety. This technique eliminates the need to modify your amp and will sound nearly as good, but it doesn't look all that great.
You will want to either find out what IEC is used in the one Boulder and match it on the other or change them both out with whatever IEC you choose. Your choice of IEC will affect the sound due to the type of prong plating (gold, silver, rhodium, etc) and how it interacts with the plating on the plugs of your power cords. There are several threads on AudioAsylum on the sound of each plating type (Duster is an expert poster on this) or you could consult Boulder and/or the power cord manufacturer for advice on which one to use.