[General Accessories] vectron:
After my review of Oppo PM-3 planar magnetic headphones, I discovered that headphone jack in the left earcup is balanced wired, despite the included single ended cables. That was actually a very interesting find, meaning PM-3 can be driven from various DAPs that support either 3.5mm TRRS (HFM wiring) or 2.5mm TRRS (AK wiring). I also confirmed that Oppo used HiFiMAN balanced wiring scheme where HFM (from the tip) is L+, R+, L-, R-, while AK (from the tip) is R-, R+, L+, L-. This means you can use a balanced 3.5mm cable going directly to HiFiMAN daps, like my HM700, or get 3.5mm (HFM) to 2.5mm (AK) adapter with a wire crossover to match the connection between headphones and your source.

While looking for a cable to support TRRS connection, I came across SuperTech 6ft balanced wired cable, available on Amazon for $7.99 HERE. $400 planar magnetic headphones with $8 cable? Yeah, you better believe it!

Arrived in anti-static bag, there is nothing special about the packaging which keep the price down. Cable has a very nice and sturdy construction, though it's a bit stiff due to a thicker shielding. I didn't experience any microphonics what so ever. Cable is terminated by two identical gold plated 3.5mm connectors with a nice looking housing, and extended with a narrow collar to perfectly fit PM-3 headphone socket. The cable length is 6ft (1.8m) which is longer than a typical 4ft (1.2m) cable. It's still acceptable for a portable use and gives you an extra length to use with a desktop equipment.

Unpacking and design details.

When you compare it to PM-3 cable, you can see that a diameter of a stock cable connector housing is nearly the same as a narrow collar of the connector used in their SuperTech cable. As a result it goes in easy and stays secure attached to the earcup.

When I tried using it with HiFiMAN HM700, it worked fine. But due to that DAP being so small and lightweight in comparison to this cable, and since headphone connector is located inconveniently on a side, I ended up pulling the plug out by accident quite a few times. I'm sure it will work better with other HFM DAPs that are bulkier and support 3.5mm balanced connector. Next I decided to move to my 2.5mm AK-wired daps, AK120ii and N5. This connection required an adapter going from HFM 3.5mm to AK 2.5mm, and I contacted Craig @Whiplash Audio with a request for one. This is a review sample, made with TWag v3 wires which in this case an overkill for $8 cable, but you can contacted him and request to use any wires for such custom adapter. Or you can make your own DIY cable adapter.

Whiplash Audio 3.5mm (HFM) to 2.5mm (AK) custom adapter.

The purpose of this exercise was to find out if balanced cable replacement can improve a sound. What I found is that Oppo's stock cable sounds nearly identical to SuperTech cable since both probably use the same type of wires. But once I introduced 2.5mm adapter into the equation - I found a slight improvement in soundstage width and depth. I wouldn't exactly call it a night'n'day change, but you can definitely hear the difference. Also, despite being 3.5mm TRRS wired connector, SuperTech cable works fine with 3.5mm HO ports (FiiO X5ii/X3ii/X1, AK120ii, QLS QA360, and Cayin N5) connected to all of my headphones with removable cables and single ended 3.5mm sockets.

In conclusion, I found SuperTech cable to have a decent build quality, to provide exactly the same sound characteristics as a stock cable, and to be able to wire your PM-3 balanced. Plus, you can use it with any other headphones as a replacement cable. For $7.99 I can definitely recommend this cable!