Re: Shaller locking tuners need string tree?
Well, I've looked around a bit online for pics of Comanches with locking Shallers, and of those that I've found , all of them have what looks to be a dark (graphite?) tree. So I don't think it was a post-factory add-on.
The question about whether it is
necessary may have more to do with personal tolerance/preference than what is "right" or "proper".
When you pluck an open string, the amount of vibration in the string that is lost to "leakage" on the other side of the nut, is directly proportional to the angle of the string as it comes over the nut. This is because the nut serves as an (imperfect) terminal point for the string. The greater the angle of the string, the more pressure that string exerts on the nut. The greater the pressure on the nut, the more likely that point will act as a terminus for the string's vibration. As the angle decreases, the pressure on the nut decreases and the more string vibration will pass through the nut.
When the pressure is sufficiently weak, open strings can rattle around in the channel cut through the nut. If there is no rattle, less bend at the nut means you'll still be losing some tone (i.e. vibration) through the nut - which will make the string sound less bright. The difference is going to more noticeable on openly plucked strings rather than on fretted strings - so the place to test isn't while you're running leads through a distorted amp - but rather plucking open strings while playing as cleanly as possible.
If a guitar has a tremolo system, I'd rather use a string tree that employs
a round fulcrum, over and against the
flatter style trees. The reason being that as the tension on the string changes with the use of the tremelo, the tension isn't as likely to snap the string at the tree because of the knife-like angle the string meets the tree. It's not really a concern of mind unless there is a tremelo system involved.
Bottom line (or as the Internet savvy crowd would say, TL;DR...) you're not going to break your guitar or twist your neck or anything by leaving the string trees off. If you aren't experiencing any rattle in the nut, and you cannot hear any appreciable tone loss, then that's that. I'd try a round string tree first because even if I can't personally hear a difference in tone, knowing that there is one - even if only my dog can hear it - would irritate my latent OCD tendancies to "make it right".
There. I've said more than anyone ever needed to say about that. lol.