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Hi all. I'm looking for a stereo power amp to replace a Rotel RB-991. The Rotel is going because, long story short, it's mains-grounded (3 prong power cable), and so is my HTPC. Adding a second mains-grounded component to my system, it turns out, introduces a loud ground loop hum that no amount of cable-swapping and re-configuring can tame. If I leave the PC off and listen to vinyl only, everything is fine - buuuuut that's not going to do, and so the Rotel has to go. So, I'm looking for recommendations for a chassis grounded (2 prong cable) power amp, ideally with 150wpc+ at 8ohms, preferably rated down to 4ohms. Some relevant info: System TV: Samsung 4k HDCP 2.2 thing that loathes handshaking with my AVR AVR: Marantz SR6010 HTPC: custom built Windows 10 machine (mains-grounded) Turntable: Technics SL1210mkII Phono Preamp: Emotiva XPS-1 Speakers: KEF Q700s, Q600c, Q400, and Q300s at the rear Budget Up to $3500 for a good solution. This may mean higher RRP, depending on which stores I can source the unit from (some being more flexible than others with price). What am I looking for? 150wpc+ into 8ohms stereo power amp (or comparable solution), capable of handling 4ohm loads, with a high enough damping factor that the bass is tight and snappy (like the Rotel). Unlike the Rotel, I need something without overly harsh or sibilant treble, and it absolutely cannot be something that is mains grounded. In my price range, that last proviso alone rules out: Rotel, Cambridge, Parasound, and Exposure. I'm sure they're all good amps, but they're not going to work for me. What I'm considering Emotiva XPA-2 Pro: heaps of power, good price, similar input sensitivity to Marantz power amps, suggesting it will work well with my SR6010, high damping factor Con: no longer distributed in Australia so there's hundreds or dollars in shipping if it breaks, and there are many stories of them breaking, also, the blue LED aesthetic is a bit too early-2000s Nokia 8250 for me Emotiva BASX A-300 Pro: cheap, could easily get 2 and bi-amp the Q700s and get better channel separation, high damping factor Con: audio quality(?), no longer distributed in Australia so there's hundreds or dollars in shipping if it breaks, and there are many stories of them breaking, blue LED aesthetic Marantz MM7025 Pro: cheap, could easily get 2 and bi-amp the Q700s and get better channel separation, guaranteed to play well with the SR6010, I know I like the Marantz sound, my preferred stockist is flexible with pricing Con: barely more power than the SR6010 (if only one used, not sure about bi-amping), not rated to anything below 6ohms, el-core transformer (does this even matter?) Marantz MM7055 Pro: more channels, guaranteed to play well with the SR6010, I know I like the Marantz sound, my preferred stockist is flexible with pricing Con: essentially a 5 channel version of the MM7025, with all the same flaws, bi-amp likely not as good as with 2 MM7025s because it's a shared power supply and is essentially bi-wiring Marantz MM8077 Pro: heaps of channels, guaranteed to play well with the SR6010, I know I like the Marantz sound, toroidal transformer, my preferred stockist is flexible with pricing Cons: a lot of money for seemingly very little gain over the SR6010 Anthem MCA225 Pro: a tonne of power, especially into low ohms (rated down to 2ohms!), my preferred stockist is flexible with pricing Con: a lot of money for the spec, 225wpc is at <1%THD, rather than a more listenable 0.08% (will this matter if the overhead is just for transients?), much lower input sensitivity than other brands (10kohms vs 22+) which may(?) mean a bad match with the SR6010 NAD C 275 BEE Pro: good price, two sets of terminals for bi-wiring Con: not much more power than the SR6010, reliability issues, harder and harder to find, low input sensitivity like the Anthem Any thoughts or additional suggestions appreciated, especially from those with first-hand experience of any of the above equipment. Cheers, Simon P.S. I'm not going to bother with ground loop isolators to bodge the Rotel into working, as it has other issues (massive draw on power up that occasionally trips the protection on my surge board, brightness, lack of remote trigger) that means it's ultimately better if I replace it.
I have added an NAD 2200 into my system, changing my NAD 302 into a pure pre-amp by removing the pre-out / main-in connects and connecting the pre-out to the inputs on the 2200, as well as moving my speakers over. The problem is I have huge electrical noise coming through from my PC - is anyone able to help? Things I have gone through: PC, NAD 302 and Nad 2200 + 2 pc monitors share an 8 outlet powerboard (http://www.dealsdirect.com.au/huntkey-8-way-powerboard-surge-protection-black/) Plugged 302 / 2200 into different power outlet from PC = noise increased PC Sound card is an Asus Xonar Essence STX sound card (Xonar) with 2 rca outputs Nad 302 pre/amplifier Nad 2200 power amp Dali 400 speakers Xonar > 302 > Dali's = No noise Xonar > 302 pre-amp out (turned OFF) to > 2200 (turned ON) > Dali's = huge noise Xonar > 302 pre-amp out (turned ON) to > 2200 (turned ON) > Dali's = even more noise Xonar > 2200 direct > Dali's = medium noise If I remove the rca's from the PC all of the electrical noise disappears - it's quite obviously the PC as when the harddrives go or it startups it's the electrical noises 'amplified' har har. Tested it with 3.5mm iphone headphone jack to RCA into > 302 pre-amp > 2200 > Dali's = no noise (with the interconnect to the pc removed) Swapped each rca cable on each channel = no difference Used different rca cables = no difference Used different rca interconnect = no difference I've bought a ground loop isolator from ebay to put inline from the Xonar rca output to the line-in on the pre-amp (or maybe the interconnect between the pre-amp and the 2200?) - http://www.ebay.com.au/itm/290843874171?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 which will arrive in a few days. Other then that.. have reconnected the speakers to the 302 and the pc and it's absolutely silent again. On a slightly amusing side note, I've realised its impossible to use the headphone output on the 302 when its a pre-amp, so aside from having a $400ish 2200 anvil unless I get this ground loop figured out (I'm guessing its a ground loop? That's what I've been googling) I'm looking to immediately get a NAD 372 so I can go back to plugging my headphones in when required.