GRADO Labs Signature S550 Headphones Review

I discovered in my career that if companies are to survive, they must continuously reinvent themselves. This applies to Audio as it does to broadcasting, cable television, streaming, and all of the exciting new technologies that we are enjoying today. It amazes me that a company founded in 1953 like Grado Labs has once once again charged into the valley of the 600, and dares to redesign pretty much every component they build. When I reviewed the new Signature S950 headphones, I was astounded by the natural character of the music and the realism they produced. Please read my review of these groundbreaking headphones HERE. I dare say that their Signature S550headphones, just the opening Salvo of their high-end headphone technology, is not only successful, but also the sweetheart of their high-end headphones.

Specifications

Transducer Type: Dynamic

Operating Principle: Open Air

Frequency Response: 6Hz - 44kHz

THD: <0.2% @100dB

SPL 1mW: 112dB

Nominal Impedance: 38 ohms

Driver Size: 50mm

Driver Matched: .05dB

Weight: 335g

Cable Type: Signature Silver Detachable

Headphone Connection: 4pin Balanced Mini XLR

Source Connection: 3.5mm w/6.3mm adapter

Cushion: B Cushion

Reference equipment

Zesto Audio Athena tube DAC + 2020 Apple Mac mini

UIT-Audio.com Powered USB cable

E.A.R HP4 tube Headphone amplifier

Linear Tube Audio MicroZOTL

Manley Labs Absolute tube Headphone Amplifier Auditioning with the E.A.R HP4 headphone amplifier

The Grado Signature S550 headphones run single-ended 3.5mm out of the box, and 6.5mm with the provided adapter. Running into the E.A.R HP4 headphone amplifier was a marvel to behold. I truly expected a dramatic decrease in sound quality and definition compared to the signature S950 headphones, which I consider an assault on the state of the art. The S550s performed with extraordinary definition and pinpoint imaging giving up a little spaciousness and image size to the much more expensive S950s. The S550 is every bit as linear and dynamic as the larger cans, with prodigious space, luxurious mids, and smooth, sophisticated highs. The best part of their performance was the precise imaging, which will be a boon to engineers and producers seeking to use these headphones as engineering monitors. I was shocked by my being able to follow the individual instruments no matter how complex it was.

The B-cushions brought the new 50mm driver closer to your ear drum than any previous signature model. This enhanced the linearity and continuousness of the music and focused your hearing into what the Musicians were doing. Thought not circumaural, the cushions are very large and lay on your ears like earmuffs and are very comfortable. I did substitute a larger pair of Grado G-cushions onto the S550s, but only managed to make the sound vague and less precise. Ear pads are easy to substitute with this model, but I do not recommend it.

The S550 headphones are very efficient, and will give you very good performance from any DAP or even any cellphone around. But on high-end gear like my system, they perform like royalty. They are light weight and very adjustable and should fit any size head. The band is made of steel, so making it wider is easy and safe.

After listening to numerous recordings, I could not find any notable flaws in the frequency response. I found the bass to be highly detailed and layered, extending down to the center of the earth. The mids were smooth and elegant and blended beautifully into the bass and highs. The high band was extended and highly detailed, but lacked some of the air and spaciousness of the top of the Line signature S950s. That said, I continue to marvel at the precision of the imaging.

Auditioning with the Linear Tube Audio MicroZOTL

Switching to The David Berning microZOTL and still utilizing the single-ended connector, the sound was very close to the HP4. The bass was slightly less detailed, but very dramatic nevertheless. Mid-band was a bit softer and was equally precise. The highs were extremely detailed and fun to listen to. The microZOTL is very close to the HP4 in every way, and is a wonderful headphone amplifier overall. It made a fantastic match with the signature S550 headphones, driving them to enormous dynamics. Its all-tube design is near state of the art, with a bit less flexibility than the HP4, but costing half as much. I highly recommend this combination.

Auditioning with The Manley Labs Absolute Headphone Amplifier

Last up was The Manley Absolute Tube headphone Amplifier. This is the only one of my headphone amplifiers that offers both a single-ended and balanced output selection. The first thing I did was hook up the single ended headphones to try to compare their performance to the other two headphone amplifiers. During single-ended testing, The Manley was warmer and more lush than the other two amplifiers, even with the tone controls set to off and with only a little bit of feedback applied. The problem with the Manley lies in the fact that when you want a truly neutral position to pick when utilizing headphones, the Manley has a drawback. It is designed to adjust to any headphone, and to maximize their musical qualities. I enjoyed using the Manley, but could draw few conclusions from the single-ended output.

The Manley, however, offers a feature that none of my other headphone amps offer. The Manley has a balanced output with a four pin connector. Utilizing a different balanced cable on loan from Grado Labs showed an immediate improvement in all parameters of the signature S550s, as compared to the other headphone amplifiers. The balanced Manley output was truly terrific with a detailed and tight base response, awesome mid band, and gorgeous extended highs. Though not entirely neutral due to the complexity of the tone controls and other features offered. Yet the result was most enjoyable. If you have a Manley headphone amplifier, you will be in headphone heaven with a pair of these great signature S550s running in balanced configuration. All of the signature series headphones are balanced so swapping cables to the balanced four pin connectors is all you need to do to get balanced performance.

For best performance, the signature S550 headphones should be run with Music for a minimum of 100 hours before doing serious listening. I detected some additional improvement over time beyond the initial break-in. As far as their performance is concerned, I have no quibbles to report.

Summary

The Grado Labs signature S550 headphones are the finest headphones I know of costing under $1000. With their new 50 mm driver and Brazilian walnut Housing, they perform wonderfully. I consider the S550 to be the sweetheart of the entire Signature lineup. You will lose a bit of image, size, and depth compared to the more expensive models, but the incredible imaging and dramatic bass more than compensate for any trivial losses. If you can run balanced versus single-ended in your DAP or headphone amplifier, you will even enjoy higher definition and tighter imaging.