The Superlux HD668B aims for a far more monitor-like approach in it presentation. The sound is closer to a good closed monitor than to the very open AD700. It does not sound nearly as warm and as weighty as the AD700, and is quite thin on the mid bass to low mid region. If you are looking for full-sounding mids or midbass like the HD600 and HD650, you really should look elsewhere. True to its purpose as monitoring headphones, most parts of the frequency from bass to treble have a great control and balanced amount to it. The bass is more compact than AD700’s but is a bit deeper, more accurate, more detailed, and has a little bit more punch. All in all, the HD668B is the more accurate and neutral headphone between the two, however, it is also less open and airy-sounding than the AD700. For those who love the open sound, the Superlux can sound a bit closed-in at times and even sounds a bit hollow in some setup due to its thin low mids presentation. Though not necessarily very power hungry, synergistic amp can do wonders to them as they are quite revealing. In my experience, I prefer a warm and lush sounding setup with the Superlux to add some warmth to its sound signature. In terms of detail, both headphones are very detailed overall when compared to the competition at this price range. However, I found the HD668B to be a bit more detailed and transparent. In some ways, the HD668B is really quite a technical monster at this price range.
These two headphones are very good-sounding. In fact, I’m quite amazed at how good their sound quality is considering their price. In the past few years, we have seen increase an influx in choices in the higher end part of the headphones market; however, after I listened to these two headphones, I feel that budget oriented audiophiles are not necessarily left in the cold. Headphones like the Audio Technica AD700 and the Superlux HD668B have definitely raised the bar for sub-$100 headphones. Now, the budget-minded audiophiles, more than ever before, can get a great sounding headphone for less than $100, and to get a significant increase in sound quality, they may very well need double of that for better headphones, not including the additional cost of an amp. Gone are the days when Grados and Alessandro MS1 are the automatic choices for best-sounding full-size headphones under $100. Sub-$100 headphones have never sounded better.
System used for review:
Headphones: Audio Technica AD700, Superlux HD668B
Amp: Audiotrak Imamp
Source: Pioneer CD Player, Ipod Nano 1st Gen