Why do all Mahler recordings seem too bright?

Mahler included funeral marches in his symphonies and also use a large number of brass instruments. So I am not surprised some poorly done recording sounding "bright." However, there are many Mahler recordings CDs and LPs that sounds well balanced from top to bottom without any edginess or harshness.Some of the DGG recordings can sound bright, but not limited to just Mahler's work.

Since you said you're listening to Hires, you're either listening to CD or streaming digital. I wanted to expand on the mention of DG recordings. DG was way behind other record labels when converting from analogue to digital. Known for their multi-mic and close-mic'd techniques, early digital sounded bright, sometimes harsh, especially the brass section. Some 1980's CDs nearly make my ears bleed, and I have a well dialed-in system. There was good advice above to try some other recordings. A good quality master is key to reproducing classical or any music using acoustic instruments accurately and realistically.

Eventually, DG digital improved but I wouldn't consider it audiophile quality. I've found MTT recordings to be high quality, very listenable, even with their high-end extension. 

I wouldn't start changing your components, although cables do make a difference and you said yours are new and may need more run-in time. I think you should check for any vibration coming from your system. Components need to be isolated from the shelves they sit upon. Are you using any anti-vibration footers or devices? I listen to classical almost exclusively and couldn't get rid of the brightness until I removed vibration from my system. Vibration from the DAC and CDP contribute most to poor reproduction of digital. 

There are many high quality classical recordings, keep in mind early digital may have problems. I love old recordings of the great maestros and their orchestras. But sometimes I want to hear high quality so I seek out record labels and orchestras which have been recorded and mastered well.

@pwerahera 

You're welcome. It's unfortunate that DG had many of the greatest talent and performances and were unable to achieve the SQ of Decca, Philips, etc.

Regarding Levine, I consider him an excellent Mahlerian, I don't think I have any of his DG but have many of his RCA CDs (very good quality). But there it is, DG engineers managed to make the VPO sound bad, as they did too often. Abbado's Mahler with the VPO sounds wonderful, as does his early BPO. I believe some of the recordings are from the 70's and would have been recorded analogue. His BPO circa 2000 was DG digital and is quite listenable with very good performances, although the over-micd orchestra is rather 2-dimensional.

I feel the same way as you, there are some recordings that I don't listen to, even with my well set up digital playback. With streaming it's easy to find other performances with good SQ.

I don't think anybody has mentioned treating the room acoustics.

@mgrif104  do you have any room treatments? You should be using some type of absorbion to reduce standing waves. These are the mid to high frequencies and can cause music to sound bright.

And I reread your comment

it’s harsh on the top end when the dynamics are loud. I’m pretty sure it’s not my amp clipping though it sounds like it.  

When I've experienced brightness or harshness in the music it's at all volume levels, not only at loud dynamic peaks. If this is the case, @mapman may be right about your amp clipping. It's being overdriven at at loud volume.

The Sort Kones have an interesting design, it drains vibration and decouples. Nice find, I'd like to try these. 

May I go off-topic for a moment? I find many of the Bruckner digital recordings bright, and this only applies to the horns. Massed strings sound perfect, but all those mic's on the brass section ruin some performances for me.

Anybody else have this issue?

Have you heard the Ivan Fischer/BFO Bruckner 7 on Channel Classics?

No, but I've heard the outstanding sonics of his Maher cycle. Will check it out on Qobuz.

The close and multi-micd Bruckner is not always what I consider bright, but the brass section can also be too forward in the mix. They're the loudest instruments and there's no need to emphasize them.

@kr4 I wasn’t addressing brightness in the Ivan Fisher recordings, should have separated the two thoughts. My issue is with many modern day Bruckner digital recordings. There is emphasis on the brass (trumpets and trombones) due to over mic’ing or in the mix. The recordings are not balanced in a ff or fff passage. Adagios are usually well mixed.

The reason I mention Bruckner is due to the large scale orchestra close in size to Mahler. I’ve seen quite a few Bruckner performances where 5 trumpets and 5 trombones are used. That's a lot of microphones being used for recordings.

Typically the second movement such as an adagio is well balanced and can sound heavenly. Bruckner wrote such beautiful adagios.

Why do you corelate the number of instruments with the the number of microphones?

Because some engineers in the heyday of multi mic'ing would place a mic on each individual instrument instead of 2 or 3 per section. Some conductors, particularly Karajan liked to be involved in engineering the production process. He wanted everything micd.