Portable amp for RE0 + Sennheiser HD25-1 IIs.

I've heard that the filo e5 has helped the RE0s get some more thump in its bass. I think that a filo e7 would probably be even better.

You can usually find LODs on amazon but if you want a quality LOD... there are probably over 100 different ones that people will recommend with various prices. I'm no expert but just my $0.02

I would say to keep in mind that, at this stage, you have no reason to go out and spend more than $100 on your amplifier. In fact, I would only suggest picking up a FiiO E7 because it will give you a chance to play around and experience the improvements you can get with an external DAC and amp. I think this way you can decide *having hear a sample of how much sq can improve* whether you want to upgrade later down the road.

Primarily, make sure as much of your funds go in this order: headphones>sources>amps>cables

Goodluck and welcome to headfi! Sorry about your wallet!

Nicely made LODs, at least for ipods, are gotten on ebay for around $30ish.  I use a Mini3 headphone amp I built myself with my RE0s and they pair nicely.  The Mini3 will run you $100 (no more than $140) either used here in the sale forum or on ebay - I think a guy with ebay username soldermonkey does them for a pretty fait price and has good feedback from what I recall.

There are a lot of options, so study up a bit in here and then buy what you think you'll like that's in your price range.  I can vouch for the Mini3, I think it sounds pretty good with my RE0s, but I also had to re-encode all my music to lossless, as the RE0s are very revealing of low bitrate files and also poorly recorded stuff (which I discovered I have a LOT of).

Good Luck - and I think you made very good choices in your starter headphones, I've been thinking about getting a pair of HD25s myself the past few days. 

The E5 is a decent pair for the RE0 to add a bit of warmth to the sound signature and punch to the bottom end but don't expect a massive change. The JDS Labs CMoy BB v2.02 is a very nice portable amp that has a bass boost feature that definitely adds a nice boost in low end authority to the RE0s so I can definitely recommend that if bass boost is your thing and even without using the bass boost feature, it's still a very nice amp on its own. It costs about $69 with shipping in the US so it's not terribly expensive either.

I'm not a firm believer in the effects of cabling on sound so if you're looking for an LOD for the Fuze, I suggest looking on eBay to see what you can find. I hear Fiio's L6 LOD is a nice LOD for the Fuze so I'd look into that as well.

I think you will be very happy with what you have... (that's the only way to be happy, not wanting what you don't have or need).  Your set up is fine.