I own an Alesis DM-10 electronic drum set, and dont have a ton of pro audio experience. I am curious what is a best way to record the set's line out with my computer. The drum brain has TRS connections for both the left and right channels. Trying to run into a USB audio interface from solely the right channel generates a heavily clipped and distorted sound. I was thinking that because of the TRS connections I might need a small USB Mixer. Before you ask, no I do not want to use a MIDI connection. Any thoughts?
Likely the best bet is a USB audio interface that supports line level input and has a gain control. USB mixers are generally mixers with a built-in audio interface. This will certainly work, but may be a larger thing than you need/want. Cheap USB interfaces often don't have any gain control, but it may also be possible to adjust the volume of the output on the drum synth. If so, it should be possible to avoid clipping if the USB interface is accepting anything close to line level. (If it is designed for microphones, it likely has a gain control, but even at minimum that might not work well with line level.)
This should work without trouble on any interface with a line-input. Which is really the simplest to design, much cheaper than mic preamps or high-impedance inputs, hence the very cheapest models would suffice, such as Behringer UCA222. That has unsymmetric inputs, but the only drawback in that is that it's easier for interference to creep into the signal, which isn't normally significant in a home studio situation anyway.
What you don't want to use is an interface that has only a guitar input, or only a “mic input”, as most consumer devices have.
More expensive interfaces / USB mixers obviously have their advantages too, but these are not relevant for only recording a stereo signal. Well, even there, good A/D converters make a slight difference, but hey... it's an E-drum set, it won't sound good anyway, no matter what you do...
Honestly, this sounds like you just need to turn down the volume. I didn't notice any mention of attenuation in your question. If you have recording software that has level meters, start by trying to set the drum-head output volume so the very loudest sound you can produce while playing normally does not peak above +0dB during capture/record. Bear in mind that if you are using a mic input, there is probably extra gain added: some inputs that expect microphone input can be hard-wired to add +20dB or more.
If you have good speakers for the drum unit and want to monitor the drum set through these, you can use the headphone-out to the computer which will allow you to adjust the volume separate from the main volume (according to the manual, though I did not look to see if headphone out cancels main out.)