Plywood subfloor is going to be a nominal 3/4 inch thick and likely tongue and groove. It's also quite likely that construction adhesive was applied to the joists (reduces squeaking) if the construction is at all recent. It's a real job to remove.
There is another way, and yes I've done it, many times, whenever it's necessary to get to something under a subfloor: Or to repair damaged areas of subfloor. I'm a retired finish carpenter/contractor.
If the route you propose to take is in the direction the joists run, it's simple. Locate two adjoining joists and at each end find the center of each one. Take a circular saw and set the blade for a cutting depth of, say, 7/8 inch. There will likely be a butt joint or two somewhere along the joist that will help you locate the joist center. There will also be nails holding down the subfloor, of course, to provide a guide. Pull the nails with a cat's claw tool. Snap a couple chalk lines along the length of the nail holes, then cut with your circular saw. Remove the subfloor with a flatbar. Run the wires, and use wiring staples every so often to secure the wires to a joist. Then apply construction adhesive or liquid nails (in a caulk tube) and screw your subfloor back down. You won't be able to get right up to a parti-wall, but for your purposes, close enough. At each end of the run, you should put in supports (see below).
If you're going across the joists, it's more difficult. Snap a couple chalk lines several inches apart following the route the wires will run. Wide enough so you can get an electric drill to where you can drill holes through the joists for the wiring. Then cut the subfloor along the lines and remove with a flatbar. Drill your holes and run your wiring.
Here's the important part: To patch the floor, you absolutely must provide support between the joists. Typically this is done by using scrap plywood, and half-inch or thicker plywood or OSB will do.
I'm going to try to explain and I hope it's clear. Say you cut a channel the length of the floor 6 inches wide, and the joists are 16 inches on center, for a distance between the joists of 14 1/2 inch. The supports should be about 14 inches long and about 10 inches wide. The supports go *under* the existing subfloor between the joists. Drill a couple "helper" screws dead in the middle (lengthwise), with heads protuding to hold on to so you can maneuver the support to where it needs to be. Apply construction adhesive (subfloor glue or liquid nails in a caulking gun tube) liberally along both edges where it will lap under the subfloor. Then slip it into place, lapping under the subfloor evenly on each side. Run drywall screws through the subfloor into the support every couple inches. Those "helper" screws you put into the support earlier will give you something to hold on to and apply upward pressure until the screws bite. Make sure the supports are drawn up tight. Remove your "helper" screws.Then apply adhesive along the length of the supports and replace the 3/4 thick subfloor cutouts you removed earlier (assuming you didn't bugger them up when removing them). Screw back down into the joists and supports.
For best results, you'd then apply 1/4 inch lauan underlayment plywood over the repaired subfloor to make it perfectly level. This will be necessary if you're going to lay down resilient (vinyl) flooring. If you intend to put down carpet or hardwood flooring, that won't be necessary. Though you should still trowel on "floor leveler" mix along the length of the repair. It mixes with water like mortar to fill in any gaps or unevenness.
I hope I didn't miss anything. It all sounds like a worse job than it is. But you'll have to be fairly handy with tools to tackle this job. Otherwise, get a contractor to do it.