Bought these used, in excellent shape, to use mainly for listening to FLAC files on my MacBook Pro using MPlayer X. Also ordering a Pono Player which I plan on running in balanced mode with these puppies. I noticed that Surf Cables makes balanced headphone lines for them, so I searched them out. Remarkably, I found a pair for 35 Canadian dollars. I have noticed after the first day that they seem to naturally carry a little more bass than my beloved HD 380s. Early indications are leading me to believe that the 545's soundstage is more spacious. I've already read favourable comparisons of the 545s to the HD 580s right here on Head-Fi. Super comfy. Apparently there is a intermittency issue after some age with the two pin connectors and their sockets. I haven't experienced that yet and hope not to. All I can say is that listening to Rush's 'A Farewell to Kings' at 24bit/96KHZ is a heavenly experience with the HD 545s!
I purchased these roughly 20 year old headphones around the same time I bought my AKG K712 Pro for $75 and because of that they never got as much use as they should. This is the first headphone I've owned of the Sennheiser HD 600 family, there are some notable differences in aesthetics and drivers, these are 150 ohm headphones instead of 300 ohms, the parts seem to be fully interchangeable with the HD 600/650s though. Now I am starting to spend more time with these headphones and they slowly became my second favorite headphones. I am using the Hifiman EF2A as an amp with GE tubes, the HRT Music Streamer II+, and I have tried a variety of genres, mainly electronic and acoustic.
Comfort: Comfort is one of the standout points with these headphones, they are incredibly comfortable. Actually probably the most comfortable headphone I own. Think of a HD 600/650 with much less clamp and you basically get the HD 545s comfort. The headband causes no discomfort and and the pads are soft and gently hug the ears with a mild clamp. I would probably rate them around a 9.5 out of 10 in comfort for my ears.
Build Quality: I would say these headphones are well put together, the plastic of high quality. These headphones are made in Ireland like the rest of the HD 600 family. The have replaceable cables, seems to use the same cable that is used in the HD 600. They are easily serviceable and don't require any tools to take apart, except getting the driver out of the housing. The one problem it has build quality wise has to be the channel dropout issue common with older headphones in the HD 600 family before they changed the spring material, the springs stretch out too much and the connection to the cable can become a bit loose causing occasional channel dropouts if you move around too much.
Driver and Housing
The sound on these headphones is really enjoyable to listen to once you get used to their sound. It's rich and full sounding but also quite neutral. The soundstage on these headphones is rather moderate in size. I consider these headphones quite transparent.
Bass: I'm starting with the bass of these headphones. It's a warm and rich bass with good impact with a nice natural tone to it, but it has a couple drawbacks. First is the sub-bass roll-off, it doesn't seem to reach quite as deep as either of my AKGs. The other problem with the bass is that it seems to get a bit muddled and confused on more complex bass passages.
Midrange: This is where this headphone shines soundwise. It's a rich, full, and musical midrange that is quite forward. Vocals have great clarity, presence, lushness, and a naturalness to them that is really enjoyable to listen to. Some drawbacks with the midrange is that it may be a bit too forward for some and on some systems can sound a bit brash on some sounds such as horns.
Treble: The treble is quite present in these headphones, I wouldn't say it's bright, but it's definitely not dark. I would say the treble is a little more forward than my K612 although I don't think it extends up quite as much. Sibilants can be an issue depending on the system.
Soundstage: I'm a bit mixed on the soundstage, it's rather moderate in size but has good depth and is quite 3D sounding, despite having a smaller soundstage than my K612 it sounds bigger in presence. This could be because of amplification as I get the feeling my AKGs are a somewhat held back on my current system. There seems to be some oddities with the soundstage, something isn't quite right, maybe it's the 3 blob effect that is mentioned occasionally with the HD 600 family.
Conclusion: Overall I rate these headphones highly and I feel they are a great headphone if you can manage to find them and get them for a lower price. The channel dropout is a bit of a problem with these older headphones, but it can be fixed. I have to say I am happy with these headphones but I think I am going to replace them with either the HD 650 or HD 600 in the future.