There are several factors that I consider when evaluating soundstage:
- Width is how wide left and right the soundstage is.
- Depth is how far the soundstage extends in front of you.
- Center area is how well can a headphone fill in the area in front of your face, and not just the area on the sides.
- Separation is how clearly separated are one instrument from the next.
- Imaging is how true-to-life is the reproduction of the arrangements of the band/orchestra.
Having established those parameters, the K701 scores very highly in the width and instrument separation, where you can see every instruments being individually isolated and laid out on the wide soundstage. My complaints with the K701’s soundstage is mostly with the imaging performance, as the lay out of the band and instruments doesn’t follow a logical live concert pattern. The K701’s soundstage is mostly felt on the left and right side of the head, and with very little information on the front. This may give a false impression of being immersed in the sound, as you would feel the instruments coming distinctly from left and right. But on the real world, bands and orchestras perform in front of you, not on your sides around you. And so the front/center soundstage is very important to a faithful reproduction. This is where the K701 fails heavily, as there is very little information on the front/center area of the soundstage.
Another factor that deeply disturbs the K701’s soundstage presentation is the lack of air between the instruments. The K701 separates the instruments very well with distinct distances between them. Yet, the background is almost too clean. Live recordings almost always have a small amount of air sound — that is, the sound of the air moving around the microphone. And it happens that this air is very critical for achieving a realistic ambiance. On the K701, the air sound is non existant. And while that may help give a clearer separation between the instruments, ultimately it makes the instruments disconnected without a proper “air” between them. It’s like taking a photograph of 5 people, cropping them in Photoshop, and laying them out in a perfectly clean white background. You get a very clean look at the subjects, but the photograph wouldn’t look very realistic.
The DT880’s soundstage is a little narrower than the K701, but it also improves on the aspects that I find to be more important for a realistic imaging. First, the “air” sound is not eliminated in the DT880. If your recording has that sound, it’ll come out in the DT880. Next, the center area of the soundstage is not blank as in the K701’s. The DT880 ultimately gives a more realistic view of the soundstage, with proper information coming from the front and expanding naturally to the sides.
Perhaps the biggest surprise of all is how I find the soundstage of the HD650 to be the best among the three, though under one condition: good source and amplification. On lesser systems, the K701 and the DT880 will give a more consistent, big and wide soundstage. Though they improve with better amplifiers and better sources, the improvements is limited to a certain extent. The K701 will continue to have some void in the center soundstage, while the DT880 only improves very slightly on the width and depth of the soundstage. The HD650, on lesser systems, feels fairly closed and claustrophobic. However, as you provide better amplifiers and sources, the HD650 improves tremendously. And I feel that the HD650 is the only one among the three that’s worthy of big amplifiers like the Zana Deux or the Beta22. The soundstage will expand tremendously, in the width, but also in the depth. The HD650 certainly has the most impressive depth of the three. Not only is the depth very good, but there is a very good projection of instruments that lay in the front and the back area of the stage. Like the DT880, the HD650 maintains the sound of the air between the instruments, and even more. I still feel the DT880 to lack the necessary soundstage depth to create a three dimensional image, but the HD650 is very good at this aspect. The HD650 ultimately gives the best ambiance among the three, and playing a well recorded live music like Buena Vista Social Club, the HD650 sounds far more engaging and three dimensional than the other two.