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== Good and Bad of Combined TRS to TS Stereo to Mono ==It really ISN'T good to hardwire amplifier output channels together, for both the amplifiers themselves and for the quality of the sound.Here is the issue:For the most part, MOST designers wanted good quality sound, with good, strong, accurate bass. In order to do this, you have to be able to drive the speaker, or driver in a headphone/earphone/canalphone, AND STOP IT.The way this is done is to have a very low impedance output amplifier. It will ABSORB the energy from the driver, and turn it into heat. The ratio of the designed output impedance to the actual impedance is called "damping factor." The better the power amplifier, the lower the output impedance.Well, when you strap them together, one amp channel is trying to make a voltage and the other is trying to suck it up and turn it into heat.Some amps are designed to accept this abuse, and the output devices (transistors in better amps, ICs in less expensive ones) are oversized to the point where that doesn't matter to the safety of the equipment.Often, less expensive amplifiers are protected too, by putting a resistor in series with the output. Say you are using 5534 ICs as output devices, they are very low impedance devices for ICs, but don't like to be shorted, or have their outputs tied together. So, since they should only see a MINIMUM of 300 Ohms, the designer puts 300 Ohm resistors on the outputs. This protects the IC, but kills damping factor. Problem solved.IF your amplifier is like this, and many are, shorting the channels won't matter much.If your amplifier is the first type, shorting the outputs together is bad, even if the amplifier is very over-designed and doesn't care from a damage standpoint.Imagine the extreme situation of the mis-mastered Phil Spector Beatles music of the 60s. Spector recorded the music in two track, with mostly music on one channel, and mostly vocals on the other. The intent was that in disk mastering, the channels would be mixed and a mono record would be the result. The mastering technician thought the two-track recording was supposed to be stereo, so we got the weird result, which was fairly well received; enough so that it wasn't fixed for decades.Imagine the good quality amp though. Each channel is going to be trying to eat the output of the other. It just doesn't sound good. Doing high level mixing, then adding a mono amp will sound MUCH better. Many of the outboard amps on the market can be made to do this in a quality way, and some actually have a feature where they actually mix SOME of each channel into the other to make the music sound more natural in headphones. A quick phone call to those manufacturers can get you a pure mono output.Regarding professional equipment of 25 years ago, that was about the time where impedance matching was going, going, gone. Prior to that, shorting outputs would have caused all kinds of problems, but once professional equipment left the 600 Ohm standard behind, things became easier, and there was much less chance of damage. Doing that 10 years earlier, and you could let the smoke out of the amp.[People think electronics is "smoke and mirrors." The magic is only smoke, with no mirrors. Witness what happens when the smoke comes out of the equipment, it stops working.]Modern professional and broadcast equipment is no longer 600 Ohms in and out, they are low impedance out, never more than 100 Ohms, but generally much less, less than one Ohm in many cases, and high impedance in, at least 10,000 Ohms, but generally 20,000 Ohms or more.Finally, regarding cutting off an ear bud, that isn't a good idea, as the ends of the bare wires can short. This might not be good for the amp, but even if the amp doesn't care, it isn't going to do anything good for battery life. Those small wires are very hard to work with, but if you cut it off, then cut back the outer insulation, then the outer wire, it would be safe.SOME headphones have two wires, side by side like power cord going to your lamp, but many others have coax cable, with a center conductor surrounded by the ground. There is no technical reason for this, but my Apple earbuds are wired that way.There are adapters that take the Tip-Ring-Sleeve output and turn it into RCA jacks or mono Tip-Sleeve outputs, one for left and one for right. If you do this, cutting off the RIGHT earbud shouldn't cause any trouble, then you can use either output of the adapter. If you cut off the left earbud, the right one won't play. as it is the ring, and there won't be a ring connection in the mono jack.