First up - E10 is desktop/laptop only - you can't listen to it on the go with an iPod/phone (which I'm assuming is what the OP was after)
Second - OP - you'll get both sides of the debate in the lossless/lossy debate. Simple answer is that you have to decide for yourself. Easiest way to do it is rip a cd that you know really well - use a good ripper like EAC. Rip to lossless, high bitrate MP3, 256aac if you use and iPod. Install Foobar and also the abx comparator plugin. With it you can blind test 2 formats on your own gear. If you can't tell the difference, don't worry - celebrate.
FTR I've got reasonable entry/mid-fi gear, and I can't reliably tell the difference between aac256 and lossless. So I use aac256 on my iPod Touch (more space - yay) and am perfectly happy. The secret is actually knowing yourself (your gear / your ears). There are some people (who have higher end gear and much better ears than I do)
that can tell the difference. I suspect there are a lot of others that can't, but won't bother testing themselves, and thus the "night and day" myth is continually perpetuated - especially by newcomers with golden ears who can supposedly tell on sub $200 cans. I'm not saying it's not possible - but lets just say I'm very skeptical OK
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My rule of thumb is to have everything on my home set-up as lossless (FLAC) then transcode to 256aac for my portable. May as well go lossless when hard-drive space is so cheap, and then if you ever need to transcode to a different format you're correctly doing it from lossless - rather than trying lossy to lossy (big no-no).
Third - I haven't tried the Westone4 - but I've had a few IEMs in my time so far. Go to the W4 thread, and ask in there if they
need amping (or if they benefit from it). I've come to the realisation that as far as portable goes, you only really need an amp if the cans/iems need something more to drive them. I use both my Beyers & HD600 portably from time to time (actually mainly 'transportably'). If I do - I use my PortaTube - it's because both cans actually need amping.
I also have B2 IEMs (DBA-2 clones) - most of the time now I simply use them straight out of my iPod. I occasionally use my E11 if I want to add a little bass from the inbuilt EQ - but a lot of time the extra bulk just isn't worth it. Even with my SE425s they didn't really need amping, and any benefit was simply not worth the extra bulk.
If you really want to see what a portable amp will do - go with a Fiio E11 (they are very reasonably priced and have a nice form factor and plenty of power - will drive full size cans as well), or a CMOY. Get a LOD to go with your iPod. Then you can get a taste of it without paying too much. You decide if it's worth it.
Regarding E7/E9 combo. Good entry point (I owned both). The E7 has more value as a starting DAC than an amp. I enjoyed the E7 portably for a while - but reality is that for my IEMs it wasn't actually doing much. As a dac for my netbook though, it had a lot cleaner sound. The E9 on the other hand is a good desktop amp and will drive most cans. However if you were looking for something that is entry point ~$200 just for desktop - I'd recommend the Audio-gd NFB-12 (amp/dac). It's not portable - but it does have a decent DAC and a reasonable amp. It also does higher resolutions, and is more configurable.
But as none of your current cans really need amping - why not start off with just an E11 or CMOY and take it from there. Like I said - it'll give you a taste and won't break the bank.