Pictures are taken with the s***y camera on my phone. My apologies.
Just a quick little shootout, nothing terribly extensive.
Both the speakers and headphones are playing simultaneously which gave me the ability to directly compare. Switching back and forth took less then a second. As fast as you can put on the headphones and take them off.
These comparisons are not noted at ear bleeding volumes. I'd say a little lower then "mid" volume and a little louder then a "low" volume. This was to be fair, honestly. The more power the RTA's get the more fantastic they sound and the more they fill the entire room with sound, both compared to the X1's and in general.
RTA-12B's price paid - $225
Fidelio X1's price paid - $295
FLAC > HDMI > Yamaha RX-V667 (DAC & Preamp) > Yamaha CA-1010 (Amp, Pure Class A < 20 watts) > Speaker taps for RTA-12's & 1/4" jack for X1's
Asus X54C running Ubuntu 13.04
Media player used is Rhythmbox
Philips Fidelio X1
Depeche Mode "Enjoy the Silence"
Right off the bat the first difference I notice is the RTA's have much better center imaging then the X1's. Mids are more "lifelike" in the RTA's as well. I keep hearing about the X1's mids being recessed. I'm not hearing this. Compared to the RTA's the mids in the X1's are forward. Especially in the upper end of the mids. The highs and mids kind of mash together on the X1's, in the RTA's the highs and mids are clearly defined and separate. Bass is surprisingly equal at the volume I was listening at.
Frank Sinatra "I Get a Kick Out of You" & "Come Fly With Me"
Center imaging is, well, center on both. The difference is on the RTA's Franks sounds like hes several feet in front of me and on the X1's it sounds like he's singing either right in front of my face or weirdly inside my head. Left and Right separation are further apart on the RTA's then the X1's. Instrument separation is again better on the RTA's. Again, the largest difference is the mids to upper mids are much more forward on the X1's. If you don't listen to the stereo first they sound fine, but if you go back and forth I believe this is the main cause of the RTA's sounding more realistic, IMO, then the X1's. When I first got the X1's and went back and forth between them and the Monoprice 8323 I thought the X1's sounded much more realistic. More on this later.
Slayer "Playing With Dolls"
Now this is a bit different of a story. The double kick bass drum is heard better on the X1's. Nearly as prominent as the rest of the drum kit. On the RTA's the bass drum is more in the background. Imaging is much less of an issue, as metal is a mashup of noise anyway. The more forward mids of the X1's shove the distorted guitars in your face instead of the relaxed sound of the RTA's. Tom's voice and Kerry's guitar are more mashed together on the X1's and quite separate sounding on RTA's.
Just wanted to do a quick and short shootout. Which do I like better? The Polks, by far. I will say, though, I have never had my ears on some *good* headphones. The X1's are still the best headphone I've ever heard and I am not trying to discredit them. I am very happy with my purchase and I would recommend them to anybody. If the difference between the $25 Monoprice 8323 and the $300 X1's are indication that the more you spend the more you get, I can't wait to hear a really good pair of headphones. For all I know, though, a better DAC might transform the X1's, or maybe they aren't a good fit for whatever resistor is hiding behind the 1/4" jack of the CA-1010 and running them off the speaker taps of an Emotiva Mini-X will transform them. I don't know, only spending more money and experimenting more will tell the final story. Might just be the X1's are decent headphones and I need to open my wallet further on a different pair of headphones to get the sound I'm *really* looking for. Also let it be noted that when I'm playing video games or watching movies, I adore the X1's. They just aren't what I'm looking for musically.