Sennheiser HD598Cs, http://en-ca.sennheiser.com/headphone-around-ear-home-mobile-hd-598-cs; SBAF discussion thread here. Introduced late 2016, These are closed-back versions of the open HD598/HD598SE. RRP $CAD 299.95, but currently on Amazon.ca for $CAD 183 and Amazon.com for $US 124. Can often be found cheaper; mine were $CAD 110 last Black Friday. Claimed specs: distortion @ 1 kHz < 0.2% @ 100 dB, sensitivity 115 dB/V @ 1 kHz, impedance 23 Ohms (presumably also @ 1 kHz but this is not stated). So they’re easy to drive but if impedance vs frequency (I’m not set up to measure this) has the common big peak in the bass, source output impedance of more than 3 Ohms could lead to overemphasis there. Construction seems fairly sturdy but the (nicely padded) headband is not as solid as the 598SE. Velour pads, fake leather headband cover. Light and comfortable on my size 6-7/8 to 7 head, with a fairly firm but not killing clamping force. Likely not great for big heads though: see this thread. They come with two detachable cables, a 1.2 m version with a universal one-button mic/remote and 3.5 mm plug and a thicker 3 m version with a 6 mm plug. These plug into the left earpiece with a 2.5 mm bayonet-locking plug which I think is Sennheiser-proprietary. The shorter one in particular has an annoying springiness which resists coiling or draping. Here they are modeled by the lovely Pseudodegraded, whose head is slightly smaller than mine, 6-3/4. My measurement setup and its shortcomings are described here. The short version is that I think my FR results are a bit rolled-off in the bass, take too deep a plunge at 3-3.5 kHz, and are low from c. 7 to beyond 10 kHz; and distortion, particularly in the bass, shouldn’t be trusted too far (or maybe at all – see this discussion). Frequency response For my rig: strong through the bass, strongly rolled down through the upper midrange and lower treble (below the 3-3.5 hole), and low through the mid and upper treble. The channel imbalances through the treble vary as the phones are repositioned for different measurements, but persist. In the second graph above I’ve included curves from the HD280Pro (also circumaural) and Momentum On-Ear for reference if you’ve heard those and for comparison to published curves (Innerfidelity HD280, Innerfidelity MOE, HeadRoom build-a-graph page) to illustrate the characteristics of my measurement system vs more familiar ones. I think the perception of a v-shaped response that’s been mentioned is due to the drop in the upper midrange combined with the strong bass. The treble itself is down compared to the other phones. Listening (Magni 2U), the bass on these is certainly there in quantity, but seems a bit boomy; the 280s’ bass is more recessed but more precise. Further up the range the Cses come across as smoother, although the midrange might be a bit over-influenced by the bass; but upper piano notes seem lacking. Treble seems fairly well balanced with upper midrange and has no unpleasant piercing notes. I’d agree these sound v-shaped, but maybe too much at the bass end and this pollutes the lower midrange somewhat. Bear in mind though that these comments come from someone who likes his modded K702s CSD right & left The plots below go down to 45 dB to show what happens around 35 below the 80-85 dB treble region, where they look pretty good: ridges coming down from the peaks at 8, 11, and 15.75 k are gone well before 2 ms, which should translate into treble that shouldn’t be harsh. Even if my system does underrepresent amplitudes in the mid-treble, this is still a nice result. Distortion right & left, % Not sure how significant these plots are, but here they are for completeness. Overall, I quite like these phones but find the thick bass and its effect on the lower mids a bit annoying. I did some quick listening comparisons with a friend’s NAD HP50s and AKG K550s and concluded I liked the tonal balance of the NADs best. We also compared his open-backed 598SEs: these of course sounded very different, having a nice open and detailed midrange. I must be just about the only one here who hasn’t heard the HD600 or 650 so I can’t comment on the comparisons that have been made to those.