[smk01]

The Variable Loudness Control (VLC) is a device which will allow you to increase bass/treble with respect to volume level. I wouldn't suggest trying it at a high volume level because you'll probably clip your amp & damage your hearing! You could also look at a Passive VLC which will do much the same but without all the active circuitry.
 
I don't think the Parametric EQ needs explanation. Anyway, I'd probably mess it up. Better to wait for an expert.
 
With a variable loudness control being analog all have to do is insert it in a tape monitor loop or between your DAC/source before the amplifier. Just like any other component. Don't forget to purchase an ICs for tape in/out.
 
The Parametric EQ is much the same. Or look at some (free?) software if you have a computer.

 

[kman1211]

Thanks that post did look a little too dense and intimidating at first. I'm going to read up on the AKG's now. Funny you mention STAX I was just told from Music Alchemist to really consider them..pricey but could be worth the investment. I really wanted the NAD's. Are they slow at all?? I mean I've kind of gotten used to the AKG 240's sluggishness at times so they don't have to be all stars. The 600's are just as high up on my list same concerns with speed though, also read they can be a bit hot sounding?? O2 not fast enough ?

If your looking at the HD 600, I would suggest looking into the HD 650s instead, a faster, smoother, and more refined headphone. The HD 650 isn't a slow headphone, the HD 600 is slightly slow though. I always found the HD 650 to be a perfected HD 600 despite what people say as it pretty much fixes many of the problems the HD 600 has imho, I've owned both for a while at the same time. I do find both the HD 600/650 to have a slight softness and a weird effect to their vocals that makes them less clearly defined than they should be though. The DT 150 is a good choice, better than the Senns in terms of vocals with more zest to the sound, I find the bigger soundstage wise than the HD 600 but a bit smaller than the HD 650. The DT 150 is a little slow, most apparent in the bass. The K240 has always been a little on the slow side and lacking bass extension as well as sharp treble, still oddly loved that headphone, something is addicting about its sound.

In regards to amps, I've personally found tube amps to be quicker, clearer, and dimensional sounding some reason. I'm a tube lover though as SS amps irritate my ears with extended listening.

 

[Karnitool12]

 Wonderful thank you for your impressions. What amp has good synergy with the 650, preferably a dac combo that isn't super pricey (500$ or less) Also how do you think the NightHawk would do for what I am looking for??? Thanks again.

 

[Youth]

If you're looking for an open headphone I'd also suggest HD650. It's my favourite headphone for the price and they scale like a beast. Where other headphones reach a wall at some point these headphones just keeps giving. 

 

[Karnitool12]

Ya open or closed is fine I always leaned for metal with closed because it's what I'm used to but as time goes on I just want the best overall quality for my desired sound sig. What's a good amp for the 650? 

 

[jodgey4]

Bottlehead Crack is the go-to for the HD650 if you can afford it. That plus a cheap DAC would get you realllly far.

 

[kman1211]

   Wonderful thank you for your impressions. What amp has good synergy with the 650, preferably a dac combo that isn't super pricey (500$ or less) Also how do you think the NightHawk would do for what I am looking for??? Thanks again.

I find the Nighthawk quite a bit better than the HD 650 in basically every way. I personally find the Nighthawk in a different league than the HD 650. Though some reason it does cause mixed impressions. It's a headphone you have to give a test run though.

 

[Youth]

  Bottlehead Crack is the go-to for the HD650 if you can afford it. That plus a cheap DAC would get you realllly far.

 
This would be my advice as well. I don't know many amplifiers in that pricerange but Bottlehead Crack + Speedball seems to get a lot of love with the HD650.

 

[Karnitool12]