[Caphead78]

That is fair and you should by all means get rid of anything that doesn't sound good to you. I hope you have better luck in the future and dont run into much trouble selling it!
 
Quote:

The E7 I haven't played with anything else yet. The SE420s sound great on my PPA, and fine on my Denon 3808CI. I mean I guess they are ok on the E7 too, just not as good as they should be. They have good bass on the PPA, on the E7 they sound too much like the laptop's integrated headphone port (which is what it was bought to replace).

 

[Omega]

They are IEM's.  They don't need a lot of current (and can't make use of it anyway; where would the heat go?).  Driver control is not an issue--those are balanced armature drivers in the SE420.  I would bet that you were listening at significantly higher volumes through the PPA, but with the lack of distortion cues, it can be hard to tell.
 
If you're looking for a SIGNIFICANTLY different sound signature, you need to get different things in/on your ears (ie, buy/trade for new headphones or IEM's) rather than trying to fix what is unsatisfying to you. The transducers are the primary determinant of sound character.  When you find a sound you like, and you want to go from good to great, THEN start upgrading your signal chain, amplification, etc.  Personally, I think it is silly to amplify IEM's at all.  The purpose of IEMs is portability, in a noisy environment....this will always be suboptimal compared to quiet, comfortable, powered home listening (or speakers).  Go for a good IEM that you enjoy straight from your ipod, laptop, whatever.  FWIW, I've not been terribly impressed with the Shure line, or the cheap universal UE's...but quite liked Etymotic sound.
 
Quote:

I'm using it as the DAC. Volume is not at all a problem, I have it set at 12 (of 100) and that is plenty loud. These are low impedance, high efficiency phones, they need little power. They just seem to need some heavy, fast, current to hit the real low notes, or perhaps better control of the drivers.

 

[qusp]

sorry, but I dont know where you got your info Omega, but low impedance IEMs take more current than full size headphones, less voltage, more current

 

[ClieOS]

Perhaps the question is, how 'low' that an amp should be used?

 

[dsf3g]

Personally I find that a Fiio E5 is a great addition to my Shure SCL4 iems. My source is an iPod 5G, line-out cable and Fiio E5. Flipping the bass-boost switch gives these phones just enough added un-distorted bass to hit the sonic sweet spot, IMHO.

 

[GoldfishTX]

Quote:

The total bithead does great with my SE530s.  It brings the bass that my D2+ and netbook hp out lack.  Should do just fine with your 420s, if you're willing to spend a bit more money.

This used to be my primary portable setup and yes, the bithead does very well with the SE530s.  I can't imagine that it wouldn't do the same for the 420s.  You can probably pick them up used in the forums here for not too much additional cost.  I will add this caveat, though.  I do NOT have an extensive collection of similar priced amps to compare with.  

 

[Jack C]

I still wonder why the dramatic difference in bass performance between th PPA and the FiiO E7.  The PPA being a kit/DIY amp is subject to customizations so the bass region could very well be significantly boosted, which when compared against any neutral amp like the E7 would result in a sizable difference in listening impressions.
 
Just took a look at here: http://elvencraft.com/ppav2/
 
I don't know if the above design is the same as the OP's PPA amp, but up to 15dB of boost is HUGE. That's over 30x the power output at bass frequencies versus flat. Meanwhile, the E7's max bass boost is between 4 to 5dB, depending on how you measure it as it affects a much wider range of frequencies. 
 
Jack

 

[Sycraft]

There is no bass boost on my PPA, th necessary circuitry isn't even installed. However, I am now staring to wonder if the problem is, in fact, the ear inserts. Playing around the first octave of bass seems high sensitive to head position, because it affects the seal on the plugs. I'm suspending testing until I have custom ear inserts.
 
These phones can produce the low bass I desire, I've heard them do it, however something is going on.