SOL if captive power cord?

Dremel is a tough tool to use in a sensitive device!
All the dust and tiny metal chips can be very unhealthy for your equipment.IF you do this, sealing ALL the unit with plastic and taping it so just the area you are working on is open... also it can create very severe vibrations if the cutting tool is at the wrong speed, or dull.
A better method to make a opening for the IEC socket is a 'nibbler' tool, it nibbles little rectangles of metal out. very easy to use, cost is about $15 ?? at Radio Shack.

I've hardwired power cords and have installed IEC connectors, and in both cases installation is kinda messy. I prefer the hardwiring because of the sonic degradation involved with using an IEC connector. (I've never come across a high quality one, so Alexc's mention of the Furutech got my attention.) Of course you do give up the flexibility of being able to swap cords.

One thing that hasn't already been mentioned about hardwiring: It's likely the new cord will be thicker that the one you're replacing, in which case you might have to enlarge the hole in the chassis. Drilling the hole can be tricky, in that you'd be pushing the drill bit into the chassis, and if you go too far... well, let's not dwell on that... it's just that you have to be very careful. A simpler solution is to get a power cord that's not all that thick, e.g., I've had good success with a Stealh Audio FAC, a modest cord for low-level components such as CD players and preamps. I had to enlarge the inside of the plactic grommet that secured the cord to the chassis so that the FAC would fit through--that can be done with a file--but I didn't have to drill the hole in the chassis.

A simpler but more expensive option is to have your 555 modded (sacdmods.com, for example), and to get an IEC connector installed in the process.

Well, I've cut in 2 IEC's in (gulp) ARC equipment; an amp and preamp. This is not an easy retrofit. Most of us are not experienced metalworkers. I'd *strongly* recommend practing on a piece of metal that matches the thickness of the unit in question. Mandatory, in fact...
The 'nibbler" mentioned might work on the thinner sheet metal in less expensive units, but on thicker plate metal used in more expensive stuff, it's a drill/Dremel job for shure. Dremels tools have a learning curve, to say the least. Either way, you'll generate a lot of (conductive) metal dust and filings. A post-operation blow out is *mandatory.

Was/is it worth it? On the amp, yeah. But now I have to have made some makeup pieces to cover up the really crappy job I did on the cutout. Otherwise, resale value would be a trade for a six-pack. Preamp? Well, maybe. It's a sensitive area, since attaching a p.c. that costs 50-100% of the retail price of the unit envokes a price-performance debate.

There *is a bit of hype in the p.c. market, at least in the sub-$500 area. IMHO. YMMV.

If you have to drill out the cable hole for a hard wired PC instead of an IEC it's no big deal, just don't use a regular bit. Use a step bit (Unibit) or in a pinch a hole chamfering bit (works great on thinner metals).

Neither will suddenly break through and jab the circuit board or lock up on the hole and sprain your wrist or make your CD player flop around.