[desik]

I'm in the process of getting one SR225e for heavy metal (mostly gothic/symphonic) and Sennheiser 650 for anything else. Possibly will keep just HD 650.
 
Some threads over here recommend a tube amp for Grados, to tame down their harsh highs. What would be the best bang for the buck for under $100? Does it make sense going higher than that? Does 650's go well with a tube amp for metal music?

 

[Head_case]

TTVJ Milletts Portable Amp!  That will go well with heavy metal ... you also get the pure ringing metal of the tube design
 
For under $100...tough call.  Anyone other than Fiio users know.   I'm on a Pico Slim which is superb for driving 32ohm impedance amps.  40ohm...it's starting to struggle particularly with semi-opens.   
 
Have you checked Massdrop though? They have a reasonable interesting ones.  I haven't heard these though with your combo so I am only speculating with these: 
 

 
 
Or the Alo which is less likely to get damaged in your pocket:  https://www.massdrop.com/buy/alo-tube-amp

 

[desik]

I consider desktop amps as well. What about Bravo Audio V3? Is their equalizer any better than software one?

 

[mysticstryk]

A lot of under $100 tube amps are going to have serious compromises.  However you get a small selection of quality choices under $200 from Garage1217, Schiit and Little Dot, etc.
 
(I'm in a similar situation to you, I want a tube amp for a pair of Grados I'm going to buy, plus I have an hd650.  Personally, I'm looking really hard at the new Vali 2 amp.  Plenty of power to drive a high impedance headphone like the hd650, with a lo gain switch for something like a Grado)

 

[fjrabon]

I liked Millett starving student builds with both Grados and the HD650.  As it isn't so much a brand as it is a template for building an amp, that isn't really something you could particularly look up and just buy though.  But you can certainly make a pretty good sounding one for under $100 and can sometimes buy a pre-made one for under that as well.  The Vali sounds like exactly what you're after in some ways, however, it's A) $170 and B) it doesn't have rolled off highs, which is a lot of the reason why people want tubes with Grados in the first place, to roll off harsh Grado treble.    

 

[desik]

Yeah, DIY builds are what I'm looking at right now. There are a few of them on sale in the trade forum right now. I'm a little concerned on how durable are they. I guess you should expect them to break once in a while, and be ready to do some soldering.

 

[fjrabon]

Yeah, DIY builds are what I'm looking at right now. There are a few of them on sale in the trade forum right now. I'm a little concerned on how durable are they. I guess you should expect them to break once in a while, and be ready to do some soldering.

Really just depends on the build itself. I've had mine for about 10 years now and have had 0 issues.

 

[lextek]

Schiit Vali may be a good choice.

 

[fjrabon]

Schiit Vali may be a good choice.

it's almost twice his budget though, and there isn't a used market for it either, since it just came out.  Unless you're talking about Vali 1 used, which I actually don't think is very good for the SR225e.

 

[desik]

Hmm,
How is Vali 2 different than Vali 1 and better for Grados?

 

[fjrabon]

Hmm,
How is Vali 2 different than Vali 1 and better for Grados?

It has a low gain mode with lower output impedance that's better for Grados.