AMP3 is the right candidate for your requirment. It's size is 74 X 40 x 20MM, maybe the smallest amp in the market.
AMP3 is a DAP/ AMP combo with 100 hours battery. plus a pair of stock hi fi earphone.
May owners and I have pairing the AMP3 with IE8, it is perfectly.
please refer to more comments on AMP3.
http://www.head-fi.org/forums/f15/am...8/index51.html
P.S the headfier's conclusion on the synergy of amp3 with various phones.
Good Synergy (sounds better with the AMP3 than other sources):
1. Mingo WM2 (balances the sound; too bassy with other sources)
2. KSC75
3. IE8
4. PAA-1 (buds included with the AMP3)
5. Philips SHE9500
6. Denon C710 (with impedance adapter)
7. Koss KSC-35
8. Sony MDR-F1
9. Westone ES3X
10. Denon AH-D6 Orthodynamic
OK synergy (on the same level with the AMP3 as other sources):
1. Denon C710 (sounds better, but some hiss due to sensitivity)
2. ADDIEM
3) Yuin PK3
No synergy (sounds better with other sources):
1. Etymotic ER4S
2. NuForce NE-7M
3. NuForce UF-30 (harshness and brightness accentuated with AMP3)
Maybe people can cut and paste this list when adding to it so original info is retain