The car itself does what I want it to do without any fuss. It looks good - perlescent black paint with 15" alloy wheels - and the daytime running lights along with side markers, for me, adds to that appeal. The car looks the business. AC repair service

None . .

Both rear wheel's were frozen due to rust, but the only work i did on the car was new wheel assembly on all corners, (including rotors and drums) valve cover gasket and an oil change and I couldent be more suprised with the all around performance of subarus "UNIQUE" three cylinder design. Lincoln emergency roadside Truck Repair

None . .

If I choose to later upgrade my fronts, I fear no lack of power. Mod chips available from Xtant to upgrade. jumper system for crossover adjustment which I favor as they help reduce the chances of signal loss which can occur accross the more commonly used dials. Amp runs cool and i've heard the newer models have improved upon that even more.

Screw down power terminals mainly. Aside from that you might consider upgrading your electrical system if purchasing.

Purchase this amp along with a 1001dx for $800. Though I haven't finished installing the sub amp, the 604x I just had to throw in and test out. More then enough power, while at the same time not at all lacking in sound quality. I see no future need to upgrade this piece. It's not the newer x604, this is one of the versions before Mitex took over. After adding an Audiobahn EQ I literally had goosebumps, an impressive piece.

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Havent personally used anything close this quality. A JBL and Audiobahn, both smaller and not in the same price range.

Looks good. Flexibility. Looks. Solid built quality.(although some may argue that the 604x has better built quality).

Currently briding this amp to run a pair of dynaudio speaker. It has done a great job I'll have to say.

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Alpine...Macrom...Audison...JL...

The Looks, The power, Flexibility, VERY Reliable, and its one of the best sounding amps that I have ever heard.

none that I can think of!!!!

I listened to alot of amps over a 6 month period of time. I was first going to buy a McIntosh amp, but when I heard the 604X driving some Diamond Audio Hex, I knew that I had to own the amp. The power from that amp is amazing. Although the best thing about the amp is the sound. The sound is the truely amazing thing about the amp.

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McIntosh Products and Phoenix Gold

Reliability, flexibility, power, looks, damn near everything.

None that I am aware of.

This amp is one of the best amps money can buy. It has unmatched flexibility, when installed properly it is VERY reliable, and it puts out very clean power. The ability to actively bi-amp a set of components is made possible through the built-in processing, and Xtant customer support is second to none. You owe it to yourself to give an amp of this caliber a shot. Highly recommend.

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PPI PC450, MMATS LM2100, Rockford Fosgate Power Series, Zapco Studio 100, etc. I would recommend it over all of them.

Very reliable, clean and polished power. Very flexible in use and application. Customer support is top notch. Will put cool power till all night long. And the sound...oh the sound!

There. Are. None.

One of the best audiofile products I've ever used. This amp can put out the power and make it sound REALLY good. I love the flexability of it's plug-in modules. I put in the PQM1 to tweek my components and I've never heard anything of better quality in a car. I've never had this amp cut out on me, even when playing it hard all day long on a hot summer day. I would definity recomend this amp and/or anything else from Xtant to anyone. If you're looking for refinement of sound at a desent price this is it. You get what you pay for!

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Pioneer, PPI, Sound Stream, Infinity, MacIntosh,