The Hifiman EF5 amp, while having admirable traits, is a long way from perfect. It's an inexpensive amp ($400) with many design compromises. It is no wonder that Hifiman wanted to introduce their next amp as a cost-no-object, powerful, flexible in cables/connectors, etc.... the EF6, priced considerably higher at $1600.
But the stock EF5 has some admirable traits. It has crisp and clean transients, giving you a window into the texture, and sometimes more than "a window" -- the view it gives you of classical counterpoint is like a freaking "x-ray." It's fairly dynamic too -- but hits a wall with big transients, and has muted musicality.
The modded amp sounds gorgeous with no weaknesses that I can hear (there are some trade-offs that depend on what 12AU7 tube you use with it).
I've been working with Igor Kuznetsoff for a while, and what he does could be described as "improving the implementation" of the circuit.
The stock EF5 needed power supply upgrades to give it more headroom for big transients. It needed its two opamps changed out for better ones, and signal caps had to be upgraded. Internal wiring had to be improved.
I paid $1200 total for the mods. Yeah, a lot of money to throw at a $400 amp but it seems to be worth it.
Now, the transients don't run out of steam. I can have the volume CRANKED and then a big 'ol bass drum hit comes along and feels perfectly at ease. You know how deep the bass on the LCD2 is, right? Well the EF5 feeds it powerful, deep bass that is tuneful and articulated, full of dynamic power.
And the modded EF5 is musical. All that lovely musical feeling that comes through in the nuances of singing and instrumental playing, in particular the dynamics -- the macro- and micro- dynamic ease and resolution is fantastic.
If you are interested in getting Igor to mod something, you can get into Igor's other products with less money. I find they all have his signature sound. You can buy his power conditioning boxes from TTVJ with a return policy for $80 to $90 each: http://www.ttvjaudio.com/K_Works_Silencers_p/kwo0000278.htm
If you like the Silencers, you can try his vibration isolation devices which are simple and effective and somewhere around $30 each (you would use 3 or 4 with a device).
PHOTOS of modded EF5 interior:
Edited by mike1127 - 8/22/12 at 9:53am