When it comes to passive balanced switchboxes, there aren't a whole lot of off-the-shelf options out there. It's not uncommon to just build them from scratch with a nice switch and point-to-point wiring as they're not terribly complicated.
I recently learned of a Japanese audio company called Audio Design that offers a simple but solid 3 in, 1 out balanced switchbox. The outside is a straight-forward design with a dark blue and silver aluminum box with a brushed aluminum front panel. The only control is the single selector knob up front to switch between the 3 outputs. What counts though is the inside, where there is a high-quality Seiden selector switch, some high-quality Neutric XLR jacks, and some thick copper wire... which appears to be 18 or 20 gauge.
One of my clients owns the unit, and wanted to take it to the next level. The Seiden switch is already top-notch, could stay, but we'd replace the copper wire with solder core silver wire in Teflon tubing, the XLRs with the shiny and beautiful Cardas XLRs, and the generic plastic feet with EAR isodamp feet.
I will say in advance, if you will be using the Cardas CM F and CM M XLRs, you better have a solder pot. The rhodium plating is not terribly interested in taking on solder so the areas where the wires connect need to be submerged in very hot solder for 10-15 seconds before they will be responsive. I personally use an American Beauty MP-9 solder pot for small jobs like this. I turn it on to the highest temp and let it warm for an hour before using. Kester low dross solder works well.
Once all the Cardas XLRs had been prepped, the old Neutrik XLRs were removed from the rear panel and replaced. They are the same DIN dimensions, so no need to change the hole sizes or shapes. Note that the Cardas units have pins can comply to some extent thanks to a soft material surrounding them. I don't know if this was done for vibration damping or maybe the tolerances aren't super tight, but just an observation.
The 24 gauge solid silver is then hand-sleeved in Teflon tubing and attached to each terminal. One should note to not make the paths too short or tight, as this will pull on the decks of the Seiden switch and cause there to be less surface area for the gold plated contacts to press upon. I chose to add heatshrink tubing over the solder contacts as silver will oxidize over time. The oxidation is still conductive, but it doesn't look as nice. Also it keeps the joints secure when shipping.
The feet on the unit are attached with screws into threaded holes. There are no nuts or lock washers to worry about, so switching them is quick and painless.
Whether modded or not, I think the Audio Design HAS-3LB is a very solid unit with no real shortcomings other than a slightly vanilla design. Should you wish to extract every bit of performance out of a stock unit, reach out to zynsonix.com for pricing information.
Disclosure: Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. 
