Any techniques that you all use to reduce the buzz?  I know Izotope makes plugins that can help, and I'm sure there are others, but I would prefer the cleanest possible signal directly into Sonar during tracking... Direct box ground lift hasn't worked very well, so I'm looking for suggestions.
 
Salud!

If you've got the gain turned up use a parametric EQ or two. If the amp is clean it and it hums it probably needs some work.

If the hum is consistent, a noise gate can alleviate a lot, but that shouldn't require aggressive usage (somewhere in the -50dB range).
 
Proper circuit grounding, environment, amp settings, and single coil usage will all play in heavily. Presence settings make amps highly sensitive, and single coils will then pick up every bit of EMI they are exposed to. The one I would look at first is environment, specifically appliances, transformers (variable lighting), A/C units, etc. in the vicinity or possibly on the same outlet circuit as the amp. Things not necessary should be off. If you have a single coil available, find the worst offender and adjust presence/positioning to minimize the EMI received (pickups facing away from monitors, PA's etc.)

I use single coil guitars all the time . if I'm getting most of my hum when I'm not playing during a section I will usually slice and dice my guitar tracks where I'm not playing to slip edit out the offending hum .
 
Sometimes if you move your guitar to the left or the right you may be able to find a sweet spot where there is less hum .
 
 
I don't know what version of SONAR you have.  You may already have The Sonitus Gate as a Cakewalk included plugin .That one works pretty good . Or you may have The PC 4K/EXP GATE in your Pro Channel ...
 
all the best ,
 
Kenny

As already stated, the environment is a big part of this. I've normally been able to manage guitar noise with gates and eq. Do you mean hum or general hiss and crackle? If you are getting excessive hum from the amp there may be a problem either in the amp or the environment. If you still get it with the guitar unplugged it's probably in the amp.

Sometimes this helps:
Turn the power plug of your amp 180 degree.
For all devices use the same wall socket. Because there are small voltage differences between wall sockets that sometimes produce hum. Especially with analog devices.
 

Yup It can be a war man.
But there are always a few things you can try. Here's my list:
 
1 - Back off the gain. I see way too many guitarist crank their pre amp volume to 10. While it might sound thick and distorted to your ears, others will hear "A can of Bee's". So turn the pre amp volume down a little bit.
 
2 - Move your amp. Bringing it somewhere  besides in front of a 24 inch LCD monitor (The ones that love interference).
 
3 -Use a short cable from guitar to amp. I Don't think I need to cover this one, you understand. You don't want to be a human antenna or help land any aircraft, so use smallest cables possible. (im not talking using a 1 ft. Patch cable here :-) but seriously, 8 feet or shorter is all you need.
 
4 - Roll off the treble. though this aint going to win you any sonic awards, it will help mask/slightly hide some of the buzz.
 
5 - Have your amp looked at and gone through by a reputable service tech.

Single coil pickups are often a source of hum. As has been noted some things that can be tried.  
 
Effect units can also cause it or the cabling between the effects boxes.  When I was working as an amp tech, I had many cases of someone bringing an amp for repair because it hummed and it turned out the amp was OK - it was something other than the amp causing the hum.  DO NOT use cables with connectors that are "molded" (e.g. plastic) rather than metal as they can be a source of the hum problems.  Also, good grade cables.  I may go overboard but all I use is George L's cables. 
 
Finally, the hum may be a "ground loop" hum to troubleshoot.  

Thank you all!  Good suggestions to work with.  Probably should have included a bit more info in my OP about the gear that I use causing issues:
 
Tele (single coil hum in all its glory) and Gibson SG (one single coil and one humbucker)
Tweed Deluxe clone head to Lopoline Cab with Weber 12" 
Vox Pathfinder to Fender cab with 15" JBL
Fender Bandmaster head to Fender cab with 15" JBL or Lopoline cab
Assorted Fender and Gibson balanced and unbalanced cables
Pedal board with stomp boxes not used when recording
All plugged into various power strips on three different outlets
Low level lighting(X-mas string lights, LED table lamps etc) and frig approx 12-15 feet away from recording set up
 
I was doing some comparisons on low level noise into Sonar with various scenarios, including using a preamp and/or active direct box, using amp line out,  simple mic'd Shure SM57 and other condensers--- ALL options seemed to show some noise on the meters with gear is idling(not playing). The lowest noise level I could come up with was guitar direct into the AI... very tolerable, but the tone is suspect-- I prefer a clean signal with colorations from preamp, amp heads etc.
 
Thx again
Salud...
 
 

Start with "All plugged into various power strips on three different outlets" using a minimalist approach and go from there. You want to build up knowing you are on a common ground, then analyze environment.