Very Important Maintenance/Options

We want to make sure that you get a long service life out of your component. We do a number of ‘unseen’ tasks when we modify your audio component such as:

These are just some of the checks. Then there are recommended maintenance items, not included with our standard installation charge. In addition these are priced to install with other modifications - these are not stand-alone charges which are higher.

Thermostat switches - control three fan speeds and overheating shutdown in DH-500. These have not aged gracefully. We are seeing a high failure rate. Think of their age. Some arrive here looking good externally and some not so good. We worry about all given the age. Replacements(4) installed with new thermistor too in DH-500 for $110, (2) on DH-200/220/XL-280* for $59  Kit parts are available at $10/ea. In addition we provide a small amount of Silicon thermal grease as shown below.

*XL-280/XL-600s are unlikely to need attention at their lesser age but if you want to insure reliability for the long haul it is the same price as the DH-200/220, but XL-600 would be only $85.

Silicon heatsink compound, that white coating between power mosfets and heatsink, drys out to nearly dust on aging amps. We ‘repack’ the power mosfets with new high-performance silicon ‘grease’ to restore efficient heat transfer to the heat sinks allowing each individual mosfet transistor to run cooler which is a good thing. DH-500 is $100, DH-200/220/XL-280 is $65

<<Geez you don’t really want to mess with this nasty stuff do you, let us do it.

DH-500/XL-600 PACKAGE PRICE: If you do both of the above maintenance items for the DH-500 our price is reduced to $175($150 for XL-600) due to need for disassembly in either case. No labor is saved for the smaller Hafler amps so prices are a la carte.

Fan> DH-500 only: We get a lot of questions about the fans age and reliability. They seem very reliable but they can get noisy. They can also ‘seize up’. Well, they actually get bent ‘legs’ from rough shipping and the fan blade contacts the ‘throat’ making it immobile. The four weak, soft metal ‘legs’ will distort during a hard drop because the fan motor provides enough moving mass to bend the legs in an instant stop. It worked great on our test bench then you get the amp, it overheats and then you find the fan blade is not spinning - ugh. We do not consider that a warranty issue.  We could realign it, send it back and it could happen a second time. Yikes, Argh, etc. Long story short - we can replace the fan with a ‘boxer fan’, officially tubeaxial fan(google it) which has a rock-solid fan frame. It will be quiet and reliable. >$95 installed OR $250 with the two options above.

The result of all the above is an amp that is ready for many years of additional service.


The power supply is the beating heart of your power amplifier. It must provide widely varying current outputs to the speaker load which is very reactive in nature, i.e. difficult to drive properly. Only the finest parts providing instantaneous output current over the whole audio band can hope to offer a truly faithful recreation of the amplifier’s input content.


For Hafler DH-200/220, XL-280 or custom project: 

TP-202 - similar to picture at left*, is a potent toroid power transformer with many important features for an audiophile-grade amplifier.

Technology serves sound:


TP-202: $139 kit, $195 installed if installed with other modifications. Necessary hardware is included with kit, transformer appearance may vary The TP-202 is rated for 115/230 VAC ‘wall’ voltage, 50/60Hz operation

How to use it: TP-202 can replace the original transformer for a sonic boost appreciated even with efficient speakers. In addition, TP-202 helps you construct a seriously natural sounding power supply with our new Dual-Mono capable PS-220 board, within the chassis of your Hafler DH-200/220 or XL-280.

Installer Notes: You will need to use a power drill to make the center hole for the transformer bolt (supplied). This will require a 1/4"(or slightly larger) hole. DH-200/220 requires that the fuse holders be moved away from the center of the amp, a tiny bit, if you are going to use the original Hafler boards. Our PA-XX series front-end boards have PCB mounted fuses so that this is not an issue if you are installing or have previously installed these terrific circuit boards in your amp, i.e. you remove the fuse holders completely.


For Hafler DH-500 or custom project:

TP-500 is a pair of 500 Watt toroid power transformers. These transformers will indeed fit when stacked one atop the other. The original transformer was rated at about 680 Watts, so this upgrade to 1000 Watts is significant. Not only that but you can easily fashion a dual-mono power supply with the PS-220/PS-500V2B circuit.

For sound and technical description refer to TP-200 transformer above.

TP-500(pair of 500 Watt toroids) > $249/kit, $299 installed if installed while performing any other modification in DH-500. Necessary hardware is included with kit. Transformer appearance may differ from illustration.

How to use it:

Installer Notes: You will need to use a power drill to make the center hole for the transformer bolt (supplied). This will require a 1/4 - 5/16" hole. 


For Hafler DH-200/220, XL-280 or custom project: 

LC-200 consists of two 22,000uF/80VDC capacitors with dual high-post screw mount design. The kit also includes installation hardware, wiring and instructions for installation into the Hafler DH-200 and DH-220, maybe even your own custom installation too. INSTALLATION into XL-280 would be much easier with our PS-100 or PS-220 power supply kits.

The Sound:

Then too, you'll know when you hear the LC-200 that even if these caps were the same value as the originals there would be an improvement. They're just plain better sounding. Combined with the TP-202(above) this is a smile inducing upgrade.

These are not SURPLUS parts like encountered with some eBay auctions. These are purchased new by Musical Concepts and have newer date codes. Earlier today a pair of caps already 15 years old were seen on eBay.

LC-200: $99 kit, $129 installed if you are having another mod installed at the same time. Kit includes bus wire, hook-up wires, required screws, washers and lugs. Fresh solder and detailed instructions are provided. 

If you want the dual-mono advantage then have a look at our PS-220 board options.

Alternative Bright Idea: Used with the TP-202 and our PS-220 power supply board you will have a dual-mono power supply of 40-60,000uF - far more than the 20,000uF of the original Hafler design. That sounds massive and somewhat expensive doesn't it! With our PS-220 series you can achieve dual-mono performance at an affordable price.


Try our PS-500V2B/PS-500M power supply boards for an easy to install dual-mono alternative!

For Hafler DH-500, P500 Pro & XL-600, some Adcoms, etc:

LC-500: a kit of two 39,000uF/100VDC caps, similar item shown here, installation hardware, some wiring and instructions for installation into the Hafler DH-500 and XL-600. This is a serious chunk, 78,000uF total, of energy storage compared to the 40,000uF total factory DH-500 power supply caps.

LC-500: $149 kit, $174 installed during another mod  - pair of 39,000uF/100VDC filter caps(2.5" Dia. x 5.1" high, "low post" screw terminals) Kits come with instructions, solder and necessary hardware to ease the installation. 

These are not SURPLUS parts like encountered with some eBay auctions. These are purchased new by Musical Concepts and have newer date codes. Earlier today a pair of caps already 15 years old were seen on eBay.


The Sound: See LC-200 description above.

*Adcom GFA-555 series requires four filter capacitors, two LC-500 pairs.

Some GFA-555 may requires internal modifications for a proper fit.

Alternative Bright Idea: Check out our PS-500V2B and PS-500M with our twin stacked toroid power transformer(TP-500) configuration a totally dual-mono power supply of 88,000uF(‘M’ version 60,000uF exotic caps) can be easily installed with our PS-500V2/PS-500M power supply board. That sounds massive and expensive doesn't it! You've seen far smaller power, less ambitious power supplies in $10,000 amplifiers haven't you! That puts a different light on it we think. See below!

Dual-Mono Power Supply Conversions: Interested in greater separation of individual instruments on the sound stage and greater ability to "hold together" in loud passages? Want a more effortless sound with new found stability and a "locked on" sound? Dual-Mono will provide these benefits and more! With the advent of our PS-220/PS-500 power supply boards these mods are much easier than the old style which was built up with individual parts. 

We install CARDAS Connectors, CMC GOLD RCA jacks, IEC sockets into any amp whether stock or modified. See our "Connector" page for these hi-quality RCA jacks and binding posts!

Power Amplifier Options