Experience true high-fidelity power with the Onkyo M-504, one of the brand’s most iconic amplifiers. Its striking dual green-illuminated power meters, massive transformer, and wide-bandwidth design deliver clean, effortless dynamics with excellent control over demanding speakers. A favorite among collectors and audiophiles, the M-504 combines visual impact with serious performance. Fully serviced, tested, and performing beautifully. Own an Onkyo classic, SpenCertified, and ready to elevate your system.
PLEASE READ BEFORE CONTACTING US (SAVES TIME)
Important: The specific item description for this listing is located below these details. The information here applies to all of our Craigslist listings.
IMPORTANT — PAYMENT (Craigslist Purchases)
We only accept cash at the warehouse for all Craigslist purchases.
WE ARE A BUSINESS — NOT A PRIVATE SELLER
We carry a wide range of vintage audio and video equipment. Many items are fully refurbished, tested, and cleaned. Some items are sold AS-IS, have issues, or are for parts. Each listing clearly states the condition so you always know what you are buying.
WARRANTY (ONLY IF STATED IN LISTING)
Items labeled Refurbished or SpenCertified include a 30-day warranty. Items marked AS-IS, Needs Repair, or For Parts do not include a warranty.
HOLDING ITEMS
Ready to pick something up? Message, call, or text when you are on your way. We will hold the item for one hour. Holds longer than one hour are not guaranteed.
VISIT OUR WAREHOUSE
You are welcome to browse in person. We have hundreds of vintage electronics, from fully refurbished equipment to project units. If you want us to hold something while you drive over, just tell us and we will hold it for one hour.
CASH DISCOUNT INFORMATION
Craigslist prices already include our cash discount. Website prices do not include the cash discount. If you see something on our website and plan to pay cash, contact us for the discounted price. Nearly every item is eligible for a cash discount.
SHIPPING
We do not ship Craigslist items. Craigslist listings are pickup only and cash only. If you need shipping, you may order from our website instead.
SHOP WITH CONFIDENCE
Every product’s condition is clearly stated (Refurbished, Tested, or As-Is). All items are accurately described. Not all products are listed on Craigslist. Search “SpenCertified” on Google to view our full inventory, rare finds, special offers, discounts, and how-to videos.
REPAIR SERVICES
We repair vintage electronics. There is a $125 inspection fee, which is credited toward the repair if you choose to proceed.
ADDRESS
Spencertified
456 E Juanita Ave, Suite 8, Mesa, AZ 85204
Hours: Tues–Fri: 8:30 AM – 4:30 PM | Sat: 9:30 AM – 2:30 PM | Closed Sunday & Monday
Phone: show contact info
(Call or Text)
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