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Audiophile Grade Help Needed: EX66 Monitors Source ? - Need Tube Signal Processor/Amp

post #1 of 13
Thread Starter 
So i'm looking for something to run my M-Audio EX66 reference monitors off my MacBook Pro; using the laptop's optical out. I've been working so hard on reading and learning as much as I can about Digital/Analogue converters, preamps, and any other item I think may be a fit but since i'm inexperienced in the field I really don't know what I should be looking for to process the sound the best (Digital or D/A setup). Essentially all I want is something that's going to provide the best possible quality sound for my EX66 using a optical source. I'm totally open to analogue or digital processors as long as they can feed into one of the speaker's inputs. I'd like something that can process at 24-bit/192khz to go along with the speakers and would like to keep it around $500. All the audio played on this system is 100% lossless FLAC format. For starters i've been looking at the Benchmark DAC1, Music Hall Dac25.2, GefenTV GTV-HT-AUDPROC, PeachTree Audio Decco2 Tube (lacks outputs I need), and lastly some various Hlly audio products (although they seem a little lower end). Additionally if someone would like to comment on tube systems and why they are so highly regarded in the audiophile world i'd greatly appreciate it. Let me know if you need links for the mentioned items (Can't post them yet) and the inputs and outputs on the EX66 speakers are as follows:

Analogue:
1. XLR
2. TRS
Digital:
1. S/PDIF
2. AES/EBU
*Also has an S/PDIF output*
post #2 of 13
Tubes add a layer of harmonic distortion that the human ear finds pleasing. I find that it takes the edge off of poorly encoded or low-bit-rate music. Without a tube amp (I use a headphone amp) I find some music fatiguing. The spdif input on your speakers will probably match anything you can find for under $500. Really, its the speakers and room that matter most.
post #3 of 13
Thread Starter 
Thanks Energy; that's pretty much what I was wondering about tubes. Any thoughts on which model/series of tube is a good investment? I see a lot of retailers selling stock from the 50s and 60s and claiming them to be "among the best vacuum tubes ever made". Is it true they are superior to modern tubes? Also, although the SPDIF in would work as an in on the speakers that would mean the signal would still remain digital? I was under the impression that after going through a DAC with tubes the output would be analogue if form?
post #4 of 13
Quote:
Originally Posted by HTPC_Engineer View Post

Thanks Energy; that's pretty much what I was wondering about tubes. Any thoughts on which model/series of tube is a good investment? I see a lot of retailers selling stock from the 50s and 60s and claiming them to be "among the best vacuum tubes ever made". Is it true they are superior to modern tubes? Also, although the SPDIF in would work as an in on the speakers that would mean the signal would still remain digital? I was under the impression that after going through a DAC with tubes the output would be analogue if form?

The spdif in is digital. You would not use a tube pre-amp for that. If you want the tube sound then either a tube DAC (which is just a DAC with a tube analog output stage) or use the DAC in your MBP and take the analog signal from that into something like a tube buffer (about $120) or a tube headphone amp with pre-outs (like a Little Dot MK III, $200?, they also make a DAC, btw). In your case you would need to find one with balanced outputs (XLR). I assume the TRS inputs on your speakers are balanced as well. Tubes vary in quality and the most sought after tend to be NOS (New old-stock; i.e. tubes that have never been used but made long ago). Tubes also wear out so be prepared to buy a new set every few years. The tubes in my tube buffer and my headphone amp are both NOS that I got on ebay for $5 each so its not expensive. The process of switching tubes is called "tube rolling". I haven't heard much of a diff beyond the standard harmonic distortion effect but there was some subtle change over the stock Chinese tubes. I also find tube equipment to be somewhat more "romantic" for want of a better word.
post #5 of 13
Thread Starter 
Yes, I checked and the TRS and XLR inputs on the speakers are both balanced inputs. Additionally, the digital are 24-bit/192Khz. With that said i'd really love equipment capable of keeping the FLAC based media i'm playing at the 24/192 level.
Playing off of what EnergyOwner (True Thanks to Him for his help) has laid out does anyone have any comments or equipment selection for the two options. Those being:

1. Using a Tube DAC.
2. Using the DAC in the MacBook Pro & adding a tube buffer.
3. Use the DAC in the MacBook Pro & use a tube headphone amp with
pre-outs.

Again i'm looking to feed into ZLR or TRS inputs on my M-Audio EX66s.
post #6 of 13
Quote:
Originally Posted by EnergyOwner View Post

Tubes add a layer of harmonic distortion that the human ear finds pleasing. I find that it takes the edge off of poorly encoded or low-bit-rate music. Without a tube amp (I use a headphone amp) I find some music fatiguing. The spdif input on your speakers will probably match anything you can find for under $500. Really, its the speakers and room that matter most.

It's not as simple as that, IMO.

Tubes have a certain nice character when overdriven (clipping), hence their popularity in guitar amps.

A tube pre amp should be able to be designed to work just like a class A solid state amp, IMO. If both are operated in their linear response range, and use the same topology, I have read nothing to suggest they would generate different distortion spectra.
post #7 of 13
Thread Starter 
Also, as another option does anyone have any thoughts on remaining purely digital as opposed to going with a tube? And in that case what hardware would I need to process the signal nicely going from the optical (mini-toslink) on my MBP to one of the EX66's digital inputs (SPDIF, AES/EBU)? What arguments would you make for pure digital vs. tube buffered sound?
post #8 of 13
Quote:
Originally Posted by MichaelJHuman View Post

It's not as simple as that, IMO.

Tubes have a certain nice character when overdriven (clipping), hence their popularity in guitar amps.

A tube pre amp should be able to be designed to work just like a class A solid state amp, IMO. If both are operated in their linear response range, and use the same topology, I have read nothing to suggest they would generate different distortion spectra.

Since I run my buffer and headphone amp fairly close to saturation, I guess the soft clipping provided by the tubes accounts for some of the distortion. It could also be the cheap Chinese power tubes in my headphone amp. I should roll them to see if something more expensive will make it sound more linear.
post #9 of 13
Have you tried the optical out directly to the speakers? If so did you not like how it sounds? If yes, then I would look at other options as you are doing. If you haven't tried it yet, I would do that first since it's free. Why not try the DAC in the speakers and see how it sounds? From reading the specs of the speakers, I'm betting they are using a decent DAC already.
post #10 of 13
Thread Starter 
Quote:
Originally Posted by jettore View Post

Have you tried the optical out directly to the speakers? If so did you not like how it sounds? If yes, then I would look at other options as you are doing. If you haven't tried it yet, I would do that first since it's free. Why not try the DAC in the speakers and see how it sounds? From reading the specs of the speakers, I'm betting they are using a decent DAC already.

jettore,

Since I was always told digital was so much superior to analogue I had that stuck in my mind and never tried using a 3.5mm to RCA cable from the MBP to the EX66s. Do you think it's worth a try? I guess what I was always under the impression is that you needed something in between the Macbook's output and the EX66 speakers to "process" the sound; is this at all true? With that said until now I had the toslink from the MBP feeding to an Audigy Pro Platinum sound card on my HTPC then taking the SPDIF out from it's breakout box and running that to the EX66s.

Macbook Pro (toslink) -> Audigy on Another Computer -> Audigy's SPDIF -> EX66's digital input

Since the EX66's don't support a direct optical input I could never run the laptop directly to the speakers in a digital fashion.
post #11 of 13
I would go direct from MBP(Toslink) to the EX66 spdif(Coax) input. Keep the signal digital to the speakers. Then let the speakers internal DAC convert to analog from that point forward.

Here's a converter for toslink to coax.
http://www.monoprice.com/products/pr...seq=1&format=2
post #12 of 13
Thread Starter 
Unfortunately I believe the toslink on the MBP stage is only 24-bit 96Khz. I'd really like to go for 24/192. I've been looking through various USB and Firewire external processors. I really like the look and the price point of the TerraTec DMX 6Fire. Naturally this is for the digital line i'd like to run to the speakers. I'd also like to run a second tube buffered line so i'd have the best of both worlds.
I did finally found what I wanted; that being a DAC with a digital tube output stage. As far as I can tell these devices are brand spanking new to the market. They are:

1. The Cleo Max: USB DAC (meaning usb input only): ASync USB DAC up to 192KHz with Tube Output (~$1000)
2. The Ayon - Skylla Digital DAC (Cough Cough $6850)

If anyone knows of additional units similar to this please do let me know. The Cleo Max is a kit and i'm really looking for a prebuilt unit and the Ayon is simply out of my price range.
post #13 of 13
Thread Starter 
To close the thread i'm going to give a brief overview of what I ended up doing. I ended up purchasing a new Xindak DAC-5. This is a DAC with both transistor and tube output stages. The outputs are XLR or single RCA (X2) for the tube/transistors. Inputs are coaxial and optical toslink. I went for the toslink & balanced XLRs; could not be happier. It happily accepts my optical signal from my macbook and puts out simply amazing sound from the transistors. The factory tubes need to be upgraded and by general consensious i'm going to go for either. (In order of quality level)

1. Siemens & Halske 6DJ8 NOS (Circa 1960s)
2. Tesla 6DJ8 NOS (Circa 1960s or 1970s)

I hope this thread helps someone with their computer audiophile wants and needs. Best wishes. My next post will follow up on output selection and adding pure digital, tube, and transistor outputs to the speakers in a manageable form. A word of thanks to everyone who helped in this thread!
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