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Thanks for the feedback so far. I'm a little surprised by my experience too. So far, I've had the amp running for 20+ days with at least 80+hrs if not already surpassed the 100hrs mark. The Kudos C2 has 88db sensitivity and is known to be relatively fairly easy to drive as a two way speaker. I'm running very good set of 8AWG silver plate cables handmade by another member here on Audiogon.
Coming previously from a B&W 805N paired with Yamaha amp, so far my listening with my Kudos C2 with Nuprime is that while female vocals play loud volume wise, singers like Adele and Whitney Houston sound like they ran out of lungs (lack big openness ex: during the song 'I will always love you'). When I play large orchestral music like Beethoven 5th or Dovrak New World Sym., sometimes they sound ok while other times I can't seem to get the speakers to play with enough speed, tempo and musicality. I'm guessing these symptoms are attribute by not enough 'juice' from the amp.
Surprising, a good portion (60%) of my music collection do play very well like Lindsey Stirling's Crystallize (24bit) or Elvis Presley's Remastered Collection. The 40% miss is kinda driving me crazy...
Love to hear others thoughts.
The B&W 805N were very nice speakers, but they could be on the bright side - which may explain your loss of some "openness" in the vocals with the Kudus speakers. Do you still have the B&W or Yamaha? You could try swapping either/both of these items into your current setup to see. The older Yamaha might be built better than the very small Nuprime amp. Power supply is somewhat limited in the NuPrime. This generally affects how much current is available to drive the speakers. In your case, you indicated the Kudus are relatively easy to drive, so it is probably not a concern.
Based on your comments, you’re getting good volume, but not getting enough resolution and soundstage depth. I do think power cord and fuses can help tremendously here. In your situation, I would get some Furutech FI-15 Plus (R) Rhodium connectors for both IEC and Male ends and attach them to your stock power cord. These Furutech connectors are generally $56 each. The Rhodium plated copper elements will really improve resolution as well as bass punch. I have used these particular connectors in several situations and they are excellent for the money (same rhodium/copper elements as there more expensive connectors, so it makes them an excellent value). If you wanted, you could spend $20-40 on some DH Labs power cable wire if you wanted better than the stock cord.
Combining this with a rhodium Furutech fuse will really help smooth out the sound if the stock fuse on the Nuprime amp sounds too bright. This can happen sometimes with Rhodium power cord connectors as they are very fast and transparent.
Keep in mind that the Rhodium plated stuff will require 150-200+ hours break in before sounding best.
Coming previously from a B&W 805N paired with Yamaha amp, so far my listening with my Kudos C2 with Nuprime is that while female vocals play loud volume wise, singers like Adele and Whitney Houston sound like they ran out of lungs (lack big openness ex: during the song 'I will always love you'). When I play large orchestral music like Beethoven 5th or Dovrak New World Sym., sometimes they sound ok while other times I can't seem to get the speakers to play with enough speed, tempo and musicality. I'm guessing these symptoms are attribute by not enough 'juice' from the amp.That does not sound like a power thing. If there was a lack of power, you would be describing distortion but this paragraph does not seem to do that.
So it is possible that 'tweaks' like a power cord and fuses might help. They both help in the same way: both devices can have a voltage drop across them which can result in a measurable loss of power. In addition (in particular with the power cord) if there is a loss of high frequency bandwidth in the AC power delivery, the power supply can't always charge up fully. This is because the rectifiers in the supply often only conduct for a very short time at the peaks of the 60Hz AC power waveform. Those short bursts of conduction are high frequency; if the power cord limits that the supply or supplies might not charge correctly. One consequence is that IMD can rise, which is quite audible.
IOW there really is physics behind why these things work.
You might also try different interconnect cables, shorter speaker cables, a different preamp or source! Its very hard to walk into a situation like this and simply point at one thing and definitively say that its actually the problem!!
No unfortunately nobody carries NuPrime around Seattle area. The few stores here carries Naim, Rega, Cambridge Audio, Rotel. But these brands don't make good integrated USB amplifiers that meet my digital 24bit/DSD hi-res music needs. I had a Yamaha A-U671 before, great amp for $70 but the class D sound was too cold once broken in. Was going to move to Yamaha's S-801 which is A/B class but thought I'd give NuPrime a try given the rave reviews.
I have never heard either, but I bet you could buy the Yamaha for around the same as you could sell your Nuprime for...if hopefully you can audition it in your system. It's lower power but you might like it better...but I stil stick with the give the Nuprime another month, then with tweaks it might be perfect...
I don't think power cables or fuses will achieve the results you are looking for. Most people who enjoy improvements with these upgrades are in measures of resolution. More air around instruments, more precise soundstage. They are not going to increase the sense of power or bass slam.
I recently went through the same issues. I bought these huge Legacy Focus speakers, who claim to be easy to drive. I used a Forte' 200 watt amp. And experienced the same feelings you are having now. Lack of energy, running out of steam, doesn't sound like the amp is doing it. So! I added a Crown class D amp that delivers some 475 watts! And bi-amped the speakers. A bit better, but still not cutting it. With all those watts, how could it not deliver? So, fast forward a few years and I bought a used Krell FPB-300, less power than the other two amps put together, but wow! Now this amp is doing the job! Jaw dropping improvements, bass slam is incredible! Midrange and treble is smooth and articulate.
My moral, or point, is that wattage can be a misleading rating. How much current can it flow? What is the slew rate? These are much more important numbers than wattage. A 50 watt Krell can out perform many 200 watt amps. I've heard that the 150 watt Pass Labs can drive huge speakers with ease. How to tell which amps deliver, and which do not? Well, short of listening to them at the salon, a study of the specs for the current ratings and size of the transformers, reviews that use words like slam and punch. Capacitive storage in the amp. And it's ability to double down as speaker impedance halves. I.e., 200 @ 8 ohm, 400 @ 4, 800 @ 2, etc. is a good sign of real power.
I don’t think power cables or fuses will achieve the results you are looking for. Most people who enjoy improvements with these upgrades are in measures of resolution. More air around instruments, more precise soundstage. They are not going to increase the sense of power or bass slam.
I’d opine resolution per se is probably not the overriding issue for most audiophiles, so your post is a little bit of a Strawman. I’d further opine the sonic characteristics competing with resolution are treble accuracy, overall tonality, low distortion, frequency extension, bass performance, musicality. In addition AIR is most likely a combination of resolution, high frequency extension and low distortion. What makes your statement perhaps even more of a strawman argument is the fact that many of us actually do achieve greater resolution, sense of power and bass slam with aftermarket fuses and audiophile power cords.
Geoffkait, point taken. But unless your previous power cord was completely too small, I doubt it will make a measurable increase in current flow. While two 10gauge cables may sound different, they both flow the same amount of current. If his amp is running out of power, no amount of clean power is going to change the architecture of the amp. Don't get me wrong, clean power can make worlds of difference in the quality of sound, even perceived bass slam, but not in the order of magnitude to suddenly make that amp a great match for those speakers. In fact, these are measures that should be done anyway, to get the best from any amp he may own. If these upgrades could actually increase the watts produced and current flow, then the manufacturers would be doing it at the factory to bolster their specs. No amount of fuses and cables can make a 200 watt amp into a 250 watt amp, simple as that. If that is not relavent to the OP's question, then what is?
in my own experience I touched on in my last post, I tried all manner of tweak to try and get my amp to perform. Power cable, fuse, speaker wires, and finally a second amp to drive the lower half, while I noticed improvements with each tweak, nothing suddenly made that amp a good match for these speakers. It was just too small, you can't make a silk purse out of a sow's ear.
@alpha_gt - while I agree that two different 10awg cables will still be able to flow the same amount of current, one thing that is not looked at here is how fast the amp is able to pull that current from the A/C line. In my testing with power cord connectors, I can completely change the sonic character of the sound just by using different power cord terminations. A very good example here is comparing gold plated to rhodium plated terminations. I have found that the rhodium plated power cord connectors ultimately give the best sound. The bass is very tight, punchy, and powerful. Mids/highs are very clear and clean. When you switch to gold-plated connectors on the same power cord, the sound becomes more laid back. The bass becomes more loose in a sense and loses the punch/tightness/detail. There is still a full amount of bass (which means the amp is getting the large amount of current), but in a way the slew rate of the waveforms are somewhat slowed down because the gold-plating is giving you a more gradual power transfer. The Rhodium plating will give a more immediate power transfer (in my opinion). The contact materials matter when you have two elements mating to make a power circuit.