Love / Hate relationship with vinyl?

My suggestion (no big revelation here, I know) is to look at your phono stage (which is) and see if the noise is coming from there. Also check your total system gain to see if perhaps the head-amp plus phono plus pre plus amp has too much overall system gain. If you can't eliminate it, you have four options:
1. Try an SUT. These are typically very cart specific as to the total loading you end up with, so do your research before you buy/audition. However you may find that you are also sensitive to ringing from an SUT.
2. Try a phono stage o /full function pre that has sufficient gain for the Kleos. There are several out there that will do the trick. For example, the ZYX Artisan was dead quite with a LOMC in my system.
3. As you said, try a higher output cart. If that was the route I was going, I would probably avoid an HOMC as the added mass from the additional coil windings would tend to counteract the low moving mass of an LOMC, which is one of their advantages. And don't discount an MI cart like those from Soundsmith.

I use an Ortofon 2M Black into my Shindo Auriges phono stage. Dead silent. If you have the right combination of cartridge and phono stage you should not have any hum or hiss. I used to have a Myabi Ivory with an Audio Note sut into a Cary Tube phono stage and had no hum or hiss. The hum could be a grounding issue. Ground the phono stage to the preamp and the hiss an overall gain issue.
Alan

Thanks Swampwalker. I'm trying to avoid a SUT due to the fact that they are so cartridge specific. I like my Kleos, but I guarantee you, at some point I'll want to try something else!
Currently, I'm using an older Acoustech PH-1P phono stage (designed by Ron Sutherland). For MC input it has a choice of either 61.5bd or 52db of gain (straight in from the tt I used 61.5 input). Again, I had noise at high volume. That's why I wanted to try the headamp, which I'm running into the MM input (42db of gain) of the PH-1P, using the 20db gain from the headamp).
As far as another MM (or MI) cartridge, that's definetly an option, and yes, the Soundsmiths are on my radar! Thanks for your input.

I think that you have a ground problem. Try getting device like the juice bar and plugging in all of your devices in to a single phono path (phono preamplifier, turntable, speed controller, and preamplifier ect.) so that all power cords share the same common ground. This may clear up your problem.

Louis ... I use a Lyra Kleos too, which I really like a whole lot. Been there and done it with an Ortofon 2M Black and Soundsmith Zephyr. IMO, the Kleos is much better. My electronics are an ARC phono pre (58 db gain) and linestage(12 db gain), which do a nice job. No hum or hiss.

Something else is causing the trouble. The hum could be a ground loop or maybe even the TT motor. I might have blinked and missed it, but what TT are you using?? Any possibility the TT is the source of the hum??

The hissing is something else. Could be the phono pre and/or preamp combo.