We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-18 · 6 min read · Independent comparison
If you want a single lightweight pair of closed studio monitors for personal tracking and monitoring, choose Superlux HD661; if you need a complete multi-headphone monitoring setup for a band, podcast crew, or recording session, choose Rockville PRO-M50.
• Superlux HD661 — biggest strength: A lightweight (6.72 oz) closed-back over-ear monitor tuned for deep sound field and balanced tone, with two cable lengths and a full accessory kit included.
• Superlux HD661 — biggest trade-off: It's one headphone for one listener. No amp, no spare pads, no second pair — it's a personal tool, not a shared rig.
• Rockville PRO-M50 — biggest strength: It's a system, not just a headphone: four PRO-M50 headphones plus the RHPA4 4-channel amp, with up to eight outputs and independent volume per channel.
• Rockville PRO-M50 — biggest trade-off: It's heavy (7 lb total) and overkill if you only ever monitor alone. You're paying for channels and accessories you may not need.
• Who each pick is for: Solo engineers, editors, and broadcast users → Superlux HD661. Bands, podcast teams, and studios running multiple listeners at once → Rockville PRO-M50.
The HD661 is built around a 40mm dynamic driver with a neodymium magnet, rated at 102dB sensitivity and 68Ω impedance at 1kHz. In plain terms, that's a moderately easy load — not so sensitive that it hisses on everything, not so demanding that a laptop or interface headphone jack struggles with it. The 10Hz–20kHz frequency range covers the full audible band, and the enclosed (closed-back) design is the point here: it isolates you from outside noise so you can actually hear what you're monitoring.
What it does best is focus. The airtight cups and the stated deep sound field make it a sensible pick for live monitoring, studio tracking, and broadcast work where you need isolation from a loud room. The accessory set backs that up: a gold-plated 3.5mm-to-6.3mm adapter, a 3.3 ft cable, a 9.8 ft cable, a cable clip, and a carrying pouch. Two cable lengths is a small thing that matters a lot — short for a belt pack or phone, long for a desk run. The plastic over-ear housing keeps the weight at 6.72 oz, which is genuinely comfortable for long sessions, and the carrying pouch means it travels without drama.
Who should buy it: a single engineer, editor, podcaster, or musician who wants one reliable closed monitor for tracking and reference listening, and who values light weight and a complete little kit over expandability. Who should skip it: anyone who needs to feed several pairs of headphones at once, wants swappable earpads, or wants a hard case. The HD661 is a solo instrument. If your sessions involve three other people wearing headphones, this isn't the tool.
One caveat worth naming: the spec sheet lists Bluetooth under wireless technology alongside a 3.5mm wired jack, and touch as a control method. Treat those as loose catalog metadata rather than a promise of wireless audio — the concrete, reliable signal path described is wired. Don't buy it expecting wireless freedom.
The PRO-M50 is a bundle, and you should evaluate it as one. You get four PRO-M50 studio headphones, each with a detachable coil cable, a case, and an extra ear pad, plus the Rockville RHPA4 4-channel headphone amplifier. That combination is the entire argument for this product.
Start with the headphones. Each PRO-M50 uses a 40mm neodymium driver in a closed-back, circumaural (around-the-ear) design, rated 32Ω with a 10Hz–25kHz range. The 32Ω impedance is low, which means these are easy to drive — the kind of load a phone, laptop, or interface handles without strain. The ear cups swivel, which helps them sit flat for storage and adapt to different head shapes. You also get interchangeable suede and leather earpads, so you can pick the feel and isolation you prefer, and each headphone comes with a protective travel case and a gold-plated 3.5mm plug with a ¼" adapter.
Now the amp, which is the real differentiator. The RHPA4 drives up to four headphones with independent volume control and a stereo/mono switch on each channel. It has both ¼" and 3.5mm inputs and outputs, and each channel offers dual outputs (¼" plus 3.5mm) — so up to eight headphones can run at once without splitting the signal into mush. It's bus-powered over USB with a charging brick included, and because it can run from a USB port or a power bank, it works as well on a mobile rig as on a desk. The metal housing and LED power indicator round out a unit built to be carried around.
Who should buy it: bands tracking together, podcast and streaming setups with multiple hosts, teachers running listening stations, or any studio where several people need to hear the same mix with their own level control. Who should skip it: the solo user. If you monitor alone, four headphones and a four-channel amp are four times the gear you'll use, and the 7 lb package is a lot to move for one listener. This is a collaboration tool.
• Best for a single listener → Superlux HD661. One headphone, one job, done well.
• Best for monitoring multiple people at once → Rockville PRO-M50. Four headphones plus the RHPA4, expandable to eight outputs.
• Best for light weight and long sessions → Superlux HD661. 6.72 oz versus a 7 lb multi-unit package.
• Best for easy-to-drive headphones → Rockville PRO-M50. 32Ω is a lighter load than the HD661's 68Ω.
• Best for cable flexibility → Superlux HD661. Two included lengths (3.3 ft and 9.8 ft) suit both mobile and desk use.
• Best for travel protection → Rockville PRO-M50. Every headphone ships with a case; the HD661 gets a pouch.
• Best for pad customization → Rockville PRO-M50. Interchangeable suede and leather earpads; the HD661 has fixed pads.
• Best for collaborative recording, podcasting, and band rehearsals → Rockville PRO-M50. Independent per-channel volume and stereo/mono switching make group monitoring practical.
In my opinion, the right pick comes down to how many ears you're serving. If you monitor alone — tracking, editing, broadcast, reference listening — I'd buy the Superlux HD661. It's light, closed-back, comes with two cable lengths and a pouch, and it does exactly what a personal monitor should without dragging a rack of gear behind it.
If you record with other people, I'd buy the Rockville PRO-M50. The four headphones alone would be useful; adding the RHPA4 with independent volume, stereo/mono switching, and up to eight outputs turns it into a working monitoring station. For a band or a podcast team, that's the more useful purchase, and the swivel cups, swappable pads, and cases make it practical to live with.
For one person, yes — the HD661 is lighter, closed-back, and comes with two cable lengths for flexible setups. The PRO-M50 is better described as a multi-person system rather than a superior single headphone.
Only if more than one person needs to listen. The PRO-M50 headphones are 32Ω and easy to drive on their own, but the RHPA4 is what gives you four independent channels and up to eight outputs.
The Rockville PRO-M50, at 32Ω, presents a lighter load than the Superlux HD661 at 68Ω. Both are wired; neither is a wireless headphone despite any catalog metadata suggesting otherwise.
The Rockville PRO-M50, clearly. Four headphones, independent volume per channel, stereo/mono switching, and dual outputs per channel are built for exactly that scenario. The HD661 is a single-listener tool.
Whichever way you lean, it's worth checking the current price on Amazon before you commit, since the two options sit in very different tiers of gear.
As an Amazon Associate I earn from qualifying purchases.
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
When you buy through links on this page, we may earn a commission from qualifying purchases at no extra cost to you.
Amazon and the Amazon logo are trademarks of Amazon or its affiliates. This site is an independent third-party review and is not affiliated with, endorsed by, or sponsored by Amazon or the product brands mentioned.