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Comparison/review: Denon AH551 vs. Head-Direct RE2

post #1 of 5
Thread Starter 

Just acquired some new canalphones, so I figured why not compare the two, rather than write a review on each? This won't be any novel, just some notes on the two similar phones in question: The Head-Direct RE2 (first branded phones from the people who brought many of us the Yuin/Minibox opportunity) and the Denon AH551s, the little brother (sister?) of the 700/751 lineup.

I used to own the C700s, but decided at the time that the seemed too harsh for me, particularly on mids (vocals) when compared to my favored phones at the time, the Atrio M5s. Since then, I have moved from the M5s to the Sleek SA6s as my primary in-ear phones. In fact, I sold the Atrios. The Sleeks are my idea of the perfect IEM, so far.

For starters on this comparison, I listened to a variety of music. I'm old fart, so I don't have any metal, trance, house, etc. But I do have some hip-hop (being from Philly, a major Roots fan), some indie bands, and the obvious stuff (classic rock, folk-rock, tons of female vocals, singer/songwriters, etc.). I'm not going to outline all the songs I used in my comparison.

In brief, I burned the RE2s in for 48 hours with white noise on my Creative ZVM (the white noise file happens to be on that DAP). The Denons I only burned in 24 hours, also with white noise.

I also immediately removed the silicone tips, which irritate my ears, and installed Comply T400s, which I find very comfortable and sound-worthy. Plus, they boost the isolation on any canalphone, really turning them into an IEM to a large extent. After all, I use the same tips on my SA6s, even though it does look somewhat weird.

For the comparison, I used my Zune80, which means no EQ. I also didn't bother using the Minibox, since neither of these phones are really made for amping in my view, as they are really designed for on the go listening.

Comfort, fit and finish.
Pretty close, but the RE2s win for a simple reason: Their plastic housing is much lighter and creates less downward pressure than the 551s, which are solidly built with metal (and much smaller than the CK700s). Another reason I sold the C700s was their form factor. I didn't like the way they felt, too heavy. I could have gone over the ear, but I don't cotton to that style for some weird reason. The RE2s are so small and light, you can barely feel them. Both phones look good, but as I noted, the RE2s have a much smaller driver housing (and it's round, not barrel-shaped, like the Denons). On balance, with the Comply T400s, both are very comfortable, but I would recommend a shirt clip with the Denons (my favorite in-ear phone accessory).

For $65 on Amazon, the 551s are a fantastic value (if they are still available at that price). They deliver crisp, clean highs/mids, and are packed with punchy bass. In fact, except for the PK3s, which I bought for $25 in a group buy, the 551s are the best sub-$100 phones I've ever bought, as I prefer them over the er6i, V-Moda Vibe, im616s and other sub-$100 phones.

Having said that, the $80 group buy price from Head-Direct is another tremendous value (for full disclose purposes, Fang sent me a pair to review). No idea what the RE2s will eventually cost, but they are worth at least $80, to my ears.

So when it comes to value, both of these phones (at least at those prices) are no-brainers.


Well, this is a tough call. On some tracks, I do like the jangly sound (almost a little but of a reverb effect sometimes) that the Denons deliver, though sometimes it can seem harsh (I've been told that Denon canalphones require at least 100 hours of burn-in before they calm down). For me, the harshness is usually found on female vocals, of the Ledisi variety, not Joni Mitchell. No such issue with the RE2s, which while they are detailed, deliver a much warmer sound. At first, going from the Denons to the RE2s, it seems a comedown in a strange way, yet, once you leave the RE2s in your ears for any decent length of time, their warm, musical sound signature starts to grow on you in the mid-high range. The Denons are much more in your face on this front, which some may favor. I like both, but if I had to choose, I'd probably choose the RE2s for long-term listening (lower fatigue factor).

In other words, for short bursts, the Denons offer a really nice, bright mid and treble sound. Maybe with another 75 hours of burn-in, they will deliver a less fatiguing signature. Not sure. I am not going to sell them, though I may give them to my daughter at some point for her iPod (when she finally breaks those EP630s).

The RE2s, again, seem deficient (not sure if that's the right word) when you first plug them in coming off the Denons, but that's just because they are so different. Oh, they do require some increased volume, as the Denons are very efficient, and the RE2s a little less so. But not much.

Not even close here, as the 551 bass signature is deep, punchy and a much larger part of the overall experience. The RE2s are not bass-deficient, by any means. But it's am much tighter, balanced part of the overall sound. Do I favor the Denon bass. I suppose, but I am not unhappy listening to the RE2s either. Don't know what else to say about the bass comparison, as I am one of those Head-Fiers who is limited by my technical knowledge. My ears are just not sophisticated enough, I suppose.

If I had to choose, I'd pick the RE2s for two key reasons: They are more comfortable (lighter to wear) and they never seem harsh, and over the long haul, even though their sound is a little subdued (again, not the right word) compared to the Denon sound, that's my preference when it comes to in-ear phones. Price-wise, the RE2s cost a bit more (based on the prices as of yesterday), but they offer excellent mids, good detail and enough bass to offer a very balanced listening experience.

If I could afford both, I would get both (even as my only two in-ear phones), so when I wanted that Denon sound (jangly, with a little echo, sort of like The Byrds on Mr. Tamborine man), I would have it. When I wanted a more musical, laid back sound, but with plenty of detail and strong mids, I'd choose the RE2s (for longer listening sessions, as well).

Neither phone will disappoint, at least not in the this price range. Can they compare to the Sleek SA6s, not really. But they are what they are. Two very good, fairly priced canalphones that can almost become IEMs with the Compy T400s. If I were looking for a replacement for my OEM phones, I'd pick up either of these phones, depending on personal tastes, and budget.

Hope this helps someone looking for phones in this price range. There are other reviews of the RE2s. Not as many of the 551s.



Update: As happened with the C700s, all of a sudden, I found myself wincing here and there when the 551s were in action, reaching for the volume control (to turn it way down). Just some harshness I can't seem to shake. I went for a walk to the store, and all seemed fine, but a couple of tracks came on, and the mids really bothered me. Again, I will keep burning them in (putting them back on the white noise loop for 2-3 days) and hope for the best. Switched to the RE2s and no issues. Just something about the Denon sound signature sound (at least without much burn-in) that is not good for my ears.

Of course, being as I have the SA6s and am listening to them right now, I don't even know why I am dabbling with the 551s, but it's always good to have entry level canalphones to recommend. In this case, I am even more prone to recommend the RE2s for the extra $15. But again, others love the Denon sound, so I guess I am in the minority.
post #2 of 5
It's kind of a dis-service to to not give the Denon more burn-in, as my C700 needed 200 hours. Otherwise, thanks for the review. I don't mean to be hard on you, and I do appreciate the effort.
post #3 of 5
Thread Starter 
Not too harsh (your post, I mean). I am going to really give them a true burn-in this time, not shortchange them. I may just leave them on the white noise ZVM setup for a week and forget about them. Then, come back and see what happens. I am determined to give them a fair shake on this. I guess today's experience mirrored my last one with the C700s so much, it was eerie. First, I liked them, then all of a sudden, something about their signature bothered me. But this time, more fairness is in order. I do really like the RE2, however, but they are very different phones.
post #4 of 5
It might turn out with a surprise ending with more burn-in. My mini-review of USB DAC/Amps found the D2 in 3rd place with a couple of concerns listed, and I had 185 hours on it - but by 320 hours and a pair of new opamps it was beating the 2MOVE and Pico.
post #5 of 5
Thread Starter 
Ending is here sooner than I thought.

My Sony DAP was out of juice, so I charged it and found that with a little EQ tweaking (an A816 strength), I was able to tame the 551 mids/highs, and now they sound really fantastic...for $65, an all-out steal. On the flipside, I clicked up the Clear Bass and a little of the highs on the RE2s, and they also improved, a much sweeter sound, very nice. So as much as some folks hate the EQ thing, my view is while the SA6s don't need tweaking (let the modules do it) with the Zune80, the less expensive models do need some help sounding their best. I will still continue the white noise workout for the Denons, but they are now safe from being sold. Maybe handed down to my daughter, but they have found a home.

I still favor the less boomy sound of the RE2s, but it's still close. But two very outstanding values for anyone looking for a canalphone in the low to middle price range without sacrificing quality sound.
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