Jdanielh -
The Quad 63's are a very tough act to follow - utterly boxless sound, electrostatic clarity, single-driver coherence, dipole radiation, and very nice voicing.
Personally, I'm a big fan of dipole systems. I love what dipoles do, especially when it comes to pitch definition in the bass. I sell electrostatic and dynamic dipoles - namely, Sound Labs and Gradients (interestingly, the Gradients were voiced using Quads as a reference). I'm also a fan of Maggies, and would sell them were there not already a Maggie dealer in town. But frankly the Maggie 3.6 would be more of a sideways move relative to the Quad 63's (I've owned both).
Okay, here are my suggestions in speakers below five grand retail to possibly replace the Quads. The order is alphabetical.
1. Cliffhanger Bulldog. A bit large for a mini-monitor, but very nice voicing - rich and lively, and very low box signature. This speaker is a 3-way in a size where everything else is a two-way, and it uses a very nice ribbon tweeter.
2. Gradient Revolution. Very low coloration from cabinet or room, due to dipole woofers and pressure-relief (cardiod) midwoof. Natural and non-fatiguing long term. Makes virtually all other box-looking speakers sound colored in the bass.
3. Maggie 3.6. More laid-back voicing than the Quads in the upper midrange (which I like), but doesn't quite have the low-level resolution of the Quads.
4. Martin Logan CLS IIZ. The most physically beautiful electrostat made, very nice with a good amp.
5. Sound Lab Dynastat. Hybrid with level controls for bass, brilliance, and bias - which gives great flexibility in voicing. Very smooth mids and highs with bass extension below 30 Hz, but it's not dipole bass.
Next we have five to ten grand retail, once again going alphabetical:
1. Gradient Revolution - Active version, with an extra set of bass modules. Takes the Revolution to a new level of resolution. Very convincing on full-scale orchestra.
2. Piega P-10. I haven't actually heard this speaker, but I have enough respect for Jtinn's ears that it would be on my list to audition.
3. Quad 988 or 989. The voicing is not the same as the 63's, so try before you buy. One of my customers owned both and preferred the 988, but preferred the Dynastat over either. Many say they better the 63 in some areas.
4. Sound Lab Millennium-3: Superb sound, though I wish it was taller. Voiced warm and forgiving, kind of like the Maggies, but with electrostatic articulation. Alas, very inefficient.
And finally between ten and fifteen grand:
1. Classic Audio Reproductions T-3, maxed-out version. High efficiency system that doesn't sound like a box speaker. Very nice voicing.
2. Maggie 20.1. Haven't heard it yet, but it's got a great pedigree.
3. Sound Lab Millennium-2. A bit richer timbre than the M-3, a little more efficient, a little deeper in the bass, and taller. The net result is a significant step up. I could live happily ever after with this speaker.
Like I said, the Quad 63's are a tough act to follow. You can spend many times more money and still not have more natural sound (in the latest Stereophile, Sam Tellig said the 988 sounded more musical than a 50 grand speaker he'd recently auditioned, and I could name an 80-grand speaker that's less natural-sounding than the 63's).
One last possible solution would be to buy another pair of 63's and just budget for repairs. Then you'd still have a pair to listen to if one pair was in the shop.
Best of luck to you.
