It's no surprise that these speakers don't do bass well. Their name, Cube, suggests small size, as in other cubes we know, but they're 10" diameter coaxial drivers in a cabinet barely large enough to contain them.
View attachment 39706
If those are the same coaxial drivers Zu uses in it's floor standing models, it's no surprise that they lack bass.
See the Sound & Vision review. Ignore the reviewers comments, and go straight to the Test Bench page.
Performance Build Quality Value PRICE $2,495 AT A GLANCE Plus Big, highly dynamic sound
www.soundandvision.com
S&V's frequency response curve shows a lot to dislike. They lack bass below about 350 Hz, and their response above 1 kHz is ragged, to put it politely. To be more blunt, I'd say it's frequency response makes these speakers unacceptable.
View attachment 39707
How much do you want to spend to replace what you now have? Bookshelf speakers or floor standing?
Look for 2-way or 3-way speakers with much smoother frequency response that's flat over as wide a frequency range as possible. And look for speakers that disperse sound widely over the entire mid-range and lower treble, the voice discrimination frequency range. The above FR curve doesn't show dispersion (off-axis FR), but the reviewer did say:
That's speaker reviewerese for "these speakers beam sound too much to sound good". Their "unusually focused soundstage" requires a listener to sit imoble within a tiny sweet spot to hear any stereo image at all. You'll need an audiophile-grade head vise.
I wouldn't worry about impressive sensitivity numbers. Your Zu's are very sensitive, roughly 98 dB, based on the above curve and what Zu claims. But, as you've found, that doesn't help them. Amplifier wattage is cheap, and good sounding speakers are expensive. Instead, look for reasonable sensitivity such as 86 dB or higher.
