QuadPRO-63usedQuad PRO-63 Electrostatic Speakers, Highly Upgraded and Refined, Includes Subwoofers**Please click here to check out our newly launched SkyFi Audio website with additional items for sale** This is no ordinary pair of Quad ESL63 speakers. This is their Pro-63 model, and on t...5999.00

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

no longer for sale

**Please click here to check out our newly launched SkyFi Audio website with additional items for sale** 

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 $600 within the Lower 48 US States.


Thanks for looking and please click here if you’d like to receive a list of new equipment we receive weekly. We promise not to bombard you with junk email.



This item will be professionally packaged and insured for safe transit to your home unless you opt for local pickup from our shop. Please note that all local pickup items are only wrapped with industrial strength clear cling stretch wrap if the original manufacturer packaging is unavailable.

Local pickup is available in Glen Rock, NJ, just a half hour drive from Midtown Manhattan, with convenient parking near our building.

And if you’re looking to ship to Canada, simply follow this link to view and purchase this item. We ship to Canada via UPS Worldwide Expedited service and you’re responsible for any applicable import duties and taxes.

If we don’t have the original manufacture’s packaging, we use heavy duty double-ply corrugated boxes with custom made to your item Instapak expanding foam custom inserts. In many cases this has proven to be better than the original packaging! We also use high quality fiber reinforced tape to seal our packages. Lightweight items will be bubble wrapped and shipped in a high-quality box. 

Click here for specifics on our specialized packing process that separates us from the rest.

NJ Residents or anyone picking up without a resale certificate will need to pay NJ Sales Tax.

Thanks for looking and be sure to call us at 201-879-0000 with any questions. 



SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of select high-end audio equipment. We only buy equipment the we admire and are passionate about. No mid-fi, no gimmicks, no junk.

Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. If it does not meet or exceed the original manufactures specifications, it will not be sold. We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units.

Through our sister company which is an authorized dealer for McIntosh, Audio Research, Sonus Faber, ClearAudio, Pro-Ject Audio Systems, and Sony ES, we have access to OEM parts, service, and support. If you’re local and looking for new equipment from the above-mentioned manufacturers, please drop us a line as we can arrange both sales and professional installation in the tri-state area.


We do not accept or review any offers that do not go through the official Audiogon system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please don’t message, email, or text any offers. 


We prefer working through PayPal which allows you to use a credit card, bank transfer, and their special financing to spread out payments over six months. We do not charge extra for any PayPal fees if you purchase the item at the asking price. You can also send us a personal check (which will need to clear before shipping), certified check, money order, or bank wire transfer. International clients without access to PayPal should use a bank wire transfer. 

If you’re picking up an item, we do not accept PayPal. You must pay in person with a certified check, bank check, or wire transfer. If you make a PayPal payment and are picking up the item, your PayPal payment will be returned. 


We accept trade-ins of equal or lesser value under certain conditions. Simply click here to submit your gear for full consideration. We will only consider high-end equipment from mainstream manufacturers such as McIntosh, Mark Levinson, Audio Research, Krell, etc. and will typically pass on displays, projectors, receivers, dated surround processors, and mid-fi equipment of any type. We will offer a fair value for your equipment, but keep in mind we’re running a business and will need to be able to resell the equipment at a profit after investing a great deal of time and resources in testing, certifying, repairing, cleaning, and packaging the incoming equipment. If you’re looking for top dollar, we suggest selling direct on your own.

SELL US YOUR GEAR (Working or Broken):

We’ll also purchase your used or broken gear and arrange pickup if you’re in our local market. Simply click here to submit your gear for full consideration.

SCHEDULING AN APPOINTMENT:                                                                                

We are currently operating from our shop inside our dedicated building in Glen Rock, NJ. You’re welcome to make an appointment if there’s a piece of equipment you’d like to see in operation before or after purchase. We have several well-equipped and dedicated listening areas, plus a dedicated listening studio with tons of equipment of all makes and models. We’re not a store, so please don’t make an appointment if you’re just curious as to how a speaker or piece of equipment sounds. In essence - no tire kickers please.

You can call or text 201-879-0000 with any questions or to schedule an appointment. We can also arrange to install, calibrate, and tune your newly purchased gear in your listening room if you’re local to our area. This is super useful when purchasing large speakers or heavy amplifiers. It’s also great for ensuring your new turntable is setup correctly in its final resting place.


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