I constantly found myself taking breaks during the review – simply because there is too much thump there.
 
Yeah, you got me interested

Good review Paul, lots of information. I am currently working on my Series 5 review and agree that the tuning on the three are very similar. I was also curious and reached out to Penon and TFZ to see what the difference was between the three (especially the series 3 and 5). The response I got was that all of the earphones use a titanium diaphragm driver, but the Series 5 uses a thinner and more responsive diaphragm. When doing critical listening, I heard an almost identical tuning, but with better detail, definition and separation in the series 5. And yes @Hawaiibadboy you are probably going to really dig these. They are basshead audiophile all the way. 

Thanks lads. Vince - try using a splitter and trying one earpiece from 3 and one from 5 at the same time and see if that better "definition / detail / separation" still exists. I'm not hearing it.

Hey guys, @Hisoundfi @Brooko , have you considered trying the "harakiri mod"? It decreases the bass by roughly ~2-3 dB. Many others who've tried it found that the mod made them a lot better overall, if you're willing to permanently change the sig of the TFZ 5.

I read about it - but a permanent change to a review sample (when I have to probably refer to the original sound for comparisons in the future) is not a great idea. For now I think that EQ is a much better option in my situation

I like my 1s, thumping bass and all. But this does confirm my suspicions that the higher series are not doing a heck of a lot more. Interested to see how their 7 series turns out, though.

Thanks Paul. These are exactly my toughts of Series 5. Great review.

They have now come out with a series 5S, as seen on Massdrop. I'm curious to find out what has changed between the original 5 and the 5S. I had an opportunity to audition the 5 some time ago using a variety of sources. To me they sounded great, not too much bass to my ears as oft reported by other. Separation and soundstage was very spacious, I really enjoyed listening to Hotel California live with the 5. Although to me the highs sounded quite sibilant and harsh on some tracks. If you have a chance to review the 5S, please do so @Brooko

I'd be interested to see if they've actually changed the sound sig / frequency change.

Yes, they have. It's an audible difference. They toned down the bass about 2 dB and made the treble a little sharper. Not a big fan because the treble became a bit harsh, though the bass decrease is appreciated. It seems their second revision of the TFZ 5 was just taking in the feedback from the first version (harakiri mod and filter removal). I think it would've been fantastic if they did the bass decrease without removing the filter.

@ustinj, ultimately..are they worth the asking price?