You know you can alter the EQ in settings although it doesn't have a progrock EQ setting. 

I just try my best to make up for it with a good pair of headphones and as high a rip as possible within practicality.

For sure if you compared a 128kbps file to a 320kbps file, you SHOULD hear more information.

320kbps files are fine for all your mobile devices, I would not rip to 128kbps anything....192kbps would be the minimum, understanding though that you are not hearing all the music. It's not meant for critical listening...

So it means instead of 3,000 songs on your player, maybe you only can fit 2,000 songs.....If that is a problem then stick with 128kbps.

And everytime there's something that I'd like to listen to and is not on any of the three....

Yep, I feel your pain - went through the same process myself 

I don't know if you have much classical music in your library, but if you are re-ripping your CDs, you may also want to think about fixing the Gracenote metadata that gets connected to the tracks. The default metadata is nonsensical for classical music. Who in their right mind would search for music by Mozart under "A" for Amadeus!!

Just getting into the higher quality world over the past year after years of bad quality audio.  I just got the FiiO X1 for $99.  It plays most all the hi-res file types and you can use your own memory cards.  I use some over the ear descent quality cans, Audio-Technica ATH-M40X headphones.  Sounds great, but even better when I use the line out feature into a headphone amp!

The issue I see now is not a big selection of hi-res music available...yet.  The Pono site has some hi-res albums, but a lot of CD quality digital files.  HDTracks seems to have a better selection of hi-res stuff and the website is easier to search through than Pono.

Most of my CD rips are 320 or 256.  A question for anyone, is it worth the effort to rip CDs to FLAC or is 320kb MP3 as good?  

128 kbps is extremely lossy, although a good recording engineer can make an excellent recording at this bitrate. That being the exception rather than the rule, compressing your CDs to 128 kbps typically results in annoying degradation of audio quality. 

Another key to getting good sound quality out of an iPod or iPhone is choosing a quality set of earphones. Indeed, a home stereo rises or falls depending on the speakers you choose, and the same goes for mobile audio. Some prefer sound isolating earphones, whereas others use noise canceling headphones. The pressure changes associated with noise canceling tech drive me crazy and, IMHO, do not give an audiophile experience. Others swear by noise canceling. I have been very happy with the Sure 535 isolating earphones, which benefit from dual bass drivers and a rounded high end above 16 khz that helps protect your hearing (very important). Other great choices include several models by Ultimate Ears (custom fit earphones that include professional studio monitors) and Etymotic Research (wide range of quality offerings), among others.

At home, just play your CDs so you hear all the music. When going mobile then I think 320kbps is fine in any format. It will not be as good as your FLAC rips because you will be missing pcs of the music, due to truncating or "dumbing down" the original CD. You miss hearing the tiny tid bits of music that give you the fullness, you miss for example piano and cymbal decay, with lossy files those little tidbits end abruptly. 

But again, mobile devices should not be used for critical listening nor graded that way, they are meant for going mobile with earbuds that for the most part are not the best sounding, overly bass driven IMO.

But having these devices has made plane travel so much more tolerable today....That's the good thing!

I doubt anyone can hear the difference between lossy and lossless in a noisy mobile environment.

By the way iPods do support a lossless format, it's called alac (apple lossless) and as far as I can tell it's basically flac with an extra shell. The only program I ever found that could encode them was called music bee. But if you insist on real lossless on an ipod then that's the way to go.

These days I use an iBasso DX50 which has great sound quality and horrible everything else. But I'm used to having everything else at ipod quality level so go figure.