Quad PRO-63 Electrostatic Speakers, Highly Upgraded and Refined, Includes Subwoofers

$5,099 $5,999

This is no ordinary pair of Quad ESL63 speakers.

This is their Pro-63 model, and on top of that they've been extensively modified with upgrades by Sound Modifications. They're currently mated with Gradient SW63 subwoofers and crossovers which sound incredible. 

All of this is documented in a very interesting article and review written by the owner, then published in The Audiophile Voice.

That magazine is included as part of this speaker system package, along with tons of documentation that's at least 2" thick. Reviews, manuals, service documents, and brochures, all pertaining to these specific and exact speakers!! 

True Sound modifications to these PRO-63s include:
• Replaced internal wiring with 99.99997 pure copper wire
• Replaced binding posts with Superior Electric BP30
• Replaced input capacitors with 8mf audio grade
• New grill cloths
• Improved clamp boards
• Additional damping material
• Added wire links

Gradient Subwoofers include:
• Matching serial numbers 334A and 334B
• Active crossover for RCA connections
• Active crossover for XLR connections

Also included:
• Original power cables
• Upgraded power cables
• Power distribution box
• Original grill cloths

Everything is in perfect working condition. Both speakers play without rattles or distortion even at good (Louder) levels. The subs also work perfectly and without drama or issues.

Physically everything also shows little signs of wear.

We chose to keep the grills off the units for the pictures as we're partial to the retro industrial look. They're easy to install if you choose to.

Wrinkling is visible in the plastic dust protection film if you look at a specific angle. This is very common and in no way affects the sound. We'll try to tighten the film prior to shipping with a heat gun.

If you haven't heard Quads from this era, you're certainly missing out on some of the most detailed, truthful, and engaging speakers of all time.

They don't play particularly loud, especially when compared to modern point source speakers, but they're able to deliver hair-raising midrange and detail like no other.

All of this cost upwards of $10k in the 1990's. It would take a $20k pair of Martin Logans to surpass this performance.

We have original boxes for both of the speakers, and the subs will be packed in custom boxes with expanding Instapak professional foam.

Flat fee freight for $600 within the Lower 48 US States. We ship worldwide so contact us if you're outside of this area.

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects

Kimber Kable - XLR Interconnects

Kimber Kable - Speaker Cables

Kimber Kable - Power Cords



Original Box

Not Included


Yes Included


Not Applicable


Yes - Power

Physical Condition

8 / 10

Working Condition

10 / 10

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