a resonance in my left ear

Chiming in with mark200mph, howardlee, and symphonicsoul....

Get thee to the best audiologist rated in your area for the cleaning and through test.
I found mine who was appreciative of my 'phile concerns to the point of not only dialing in on my tinnitus, but also printed out my response measurements for the frequencies he tests at.

Other than the 2 outboard eqs' I run on my various pairs, I've in my main 'puter (Win10Pro...for the time being...) I'm running the APO equalizer 
 https://sourceforge.net/p/equalizerapo/wiki/Documentation/

with the plug-in that makes it a bit more 'friendly' and/or obvious in intent....

https://sourceforge.net/projects/peace-equalizer-apo-extension/?source=typ_redirect

Either way, you can carve a notch 30db deep in your perceived resonances' center and parametric it as desired....

Free.....I like soundforge....some nice room eq 'wares as well..

There's a cute lynx app called sndpeek

https://soundlab.cs.princeton.edu/software/sndpeek/

....that allows for r/t waveforms, the big 3, inline or with your calibrat mic....

You can actually see what your DRC is doing or has done to that location of the mic.  
Obscure fun, for some.

I hope you can get to the ear issue, something 'transient' in it's nature would drive me more nutz....

Good Fortune, J

@symphonicsoul "An amplification at certain frequencies" is very similar if not identical to what I mean. I don't have any hearing loss according to the audiologist's report, or at least my hearing is currently within the normal range. My condolences for hearing difficulties like not being able to enjoy orchestra at full tilt. I listened to the LA Phil perform Bruckner's 9th last year and powerful brass music is thrilling, but would be disappointing if it were distorted. I don't notice any problem with live music at this time. 

@asvjerry I don't use PC Audio any more once I discovered the Aurender N100. I'm a bit of a purist, too, avoiding EQ. I think it sounds way, way better that way. I think I'll first try some of these other suggestions first. It would be good to have an audiologist dial in the frequency of my tinnitus and also do a thorough ear cleaning.

@magon ....A good place to start; since you're in SoCA there's undoubtedly audiologists that give you the printouts of your 'interior fq response'....

Mine is in my high end, so difficult to totally erase without wiping out the correction applied.....I consider the remnants as my 'dial tone', throw-back concept that it is.
The Aurender has gotten good comments 'round here, so enjoy.
I like my pc for it's functionality, and I've hammered it to as quiet as possible; eq is mostly handed off to some pro versions with similar traits.  Mostly used for room corrections as noted, 'tweaks' as desired, handed off to active x-overs.....

Was the LA Phil @ the Getty?  If so, I'm jealous...
Like 'live' anything, but it's the audience end response that does me in....a 'dirty white noise', even if from a well-washed and duded up crowd...*L*
Been carrying a noise-canceling headset for just that.....one gets 'looks' but turn away when they observe the absurder.... ;)

Aids have come along way in their functionality and apps....linked to your cell, literally 'tweak-able' on the fly.  I kid that I bought a Mac for my head rather than the shelf....  Like cars, motorcycles, and the like they've gotten their envelope pushed by the stage monitor ear units worn by the players....

Anyway, start with your 'on-board items' and carry on as needed or desired.

Squelch that nasty thang....👍😎
Luck, J

@magon that Bruckner must have been amazing! From what I also understand, having small/narrow ear canals can create amplification issues. When I was little, certain sounds were really loud and they say this is consistent with small canals and then later causes issues. The canals can also start to collapse with age too. I don't know, food for thought if perhaps you have narrow canals

@symphonicsoul Yeah I had a good seat for the Bruckner - slightly back and elevated a little bit (the so-called Terrace at Walt Disney Concert Hall) - actually I bought a fairly cheap ticket and ended up near the side and back of the terrace where the sound is not so good - then a couple came up and said they wanted to trade seats with us because they wanted to sit by the door - so my girlfriend and I got this good seat in the center-front Terrance. LA Phil brass is glorious. And LOUD. I love how Bruckner uses brass. Dvorak, a wonderful composer, but he buries the brass under the strings a lot of the time. By the way I played trombone in college. 

Thanks for tip on small ear canals. Judging by the fit of IEMs that work with me, I do have small ear canals. I'm going to go back to this ENT or maybe find another one and consult on all this stuff. I have an HMO so I'm not sure I can see a different ENT. He was so dismissive of my concerns and really didn't even seem to understand them. Now all these people tell me there are possible explanations.