[ctviggen]

I have Grado SR225s and use a D/A converter, AUDIOQUEST - DRAGONFLY V1.2 USB DAC:

http://www.amazon.com/AUDIOQUEST-DRAGONFLY-V1-2-USB-DAC/dp/B00H00VLZQ/ref=sr_1_1?s=electronics&ie=UTF8&qid=1443901539&sr=1-1&keywords=audioquest+dragonfly+v1.2

I use this system to listen to FLAC files at work.  I listen all day long.  I listen to a very wide range of music, although not much that's "heavy". 

I am thinking of spending $500 to upgrade my system.  I was thinking of these headphones (Sennheiser HD 650 Open Back Professional Headphone):

http://www.amazon.com/dp/B00018MSNI/ref=wl_it_dp_o_pd_S_ttl?_encoding=UTF8&colid=15LWHGA04FA5N&coliid=I1L6X2SATW057A

Or maybe a tube amp (Valhalla 2):

http://schiit.com/products/valhalla-2

I'm concerned about tube amps, though.  I've tried this one, which failed very quickly (a month?):

http://www.amazon.com/gp/product/B00A2QM5O6?psc=1&redirect=true&ref_=oh_aui_search_detailpage

I tried four different sets of tubes on that one. 

I tried this one, which lasted longer (maybe 6 months):

http://www.amazon.com/gp/product/B00A2QKTLW?psc=1&redirect=true&ref_=oh_aui_search_detailpage

On this one, I had three or four tubes. 

I'm concerned I'll buy yet another tube amp that will fail quickly. 

Should I consider a better set of headphones, tube amp, analog amp, or something else?

[Guy 13]

Hi ctviggen,
I have a pair of HD650 driven by a Bottlehead Crack.
I've used it for more than a year and no problem with the tubes and or electronics.
The headphone amplifier is a kit,
but at Bottlehead they have someone that can put it together for you.
It's not small like the ones you mentionned, but that a plus,
more room for the components to have air to cool down.

Guy 13