surprising comparison of tube preamps

It is very much a matter voicing of the equipment designer and the buyer's personal taste and matching of components.  To me, Audio Research gear has a somewhat lean and analytical sound.  Their sound has consistently been that way, so it is a house sound that I don't particularly like, but, it is a matter of taste and I respect their commitment to their sound preference.

What matters is what has the best synergy and sounds best to you. 
A word of caution though…there are times when our brain perceives different as better. Taking time, and it could be hours, days or weeks, to let it all settle and finalize your assessment is critical. 
As a side note, I had the original LS-25 and loved how it sounded. Not familiar with the MkII version…

You've brought very trivial point that is speaking clearly that you don't have to go super crazy on pricey components.

I am wondering if people have an explanation for this but, more importantly, have been looking into getting a very simple tube pre to use for the phono part of the system. Mapletree audio sells a simple preamp that I believe is a SET OTL (are all preamps OTL?).

@arhgef 

’OTL’ means ’Output TransformerLess’ and there are preamps that use output transformers. They are often used for driving a balanced line, where the shield of the cable isn’t supposed to carry any signal current at all.

This property is useful to prevent the cable from imposing an artifact of its own. If you’ve ever heard differences between cables you know what I’m talking about.

There is a standard involved (and I’m talking about this because your amplifier has balanced inputs which if favors) for balanced operation, known as AES48. None of the ARC products support this standard. In fact there are only a few manufacturers of preamps in high end audio that do.

This might be worth looking into if you want additional transparency with a sound that is also engaging.

@atmasphere I'm reading with keen interest and hoping to learn.  So is your point leading to any reason to believe that integrated units have an  advantage?  Any, or would they need to be fully balanced from input to output?  I'll just sit back and learn now.   

@arhgef - I am not suprised at all. I have an OTL headphone amp that I also use as preamp in my office system. Between the DAC and the integrated amp to the speakers. Although one more gain stage is not ideal, the results are clear: The more of the total gain made by the OTL, the better the sound. It might even improve the sound in my main rig, but is not practical to use there (maybe, I should give it a try). I also agree that AR can be a bit lean and analytical, I have other tube gear with more bloom and warmth, which I like (to an extent). I think the great thing about OTL is relative simplicity. So I am sceptical about 'simulations' (but have not heard your example).

Great advice in this thread on several fronts.  Take some time to settle into the new sound.  Sometimes different sounds better at first but given time, you might start to notice you aren’t as in love with the new sound as you thought.  Synergy in your system is key, if your Mac is designed to operate best with balanced inputs, that will play a role in how well a pre integrated with your amp.  Simplicity, synergy and thoughtful design often win over price, great advice that you don’t need to brake the bank to get a sound you love from your system if you know what you like and are thoughtful about the components you buy. 
 

good luck!

This is exactly the question I've been researching. I put a $400 Schiit Valhalla 2 tube headphone amp in place of my SS preamp. It sounded good from the start but really opened up when I configured it differently. I run the Valhalla with no attenuation, bought a Schiit Kara, and use it in passive mode as a volume control. 

Now I'm looking at upgrading that config with an LTA Velo headphone amp/preamp. I'm also looking at some others. But I agree that the simplicity of the design is key.

The Rogue Audio RH-5 head phone amp is highly regarded. Used by many as a line stage pre. Occasionally they pop up on the used market. 

So is your point leading to any reason to believe that integrated units have an  advantage?  Any, or would they need to be fully balanced from input to output?

@akgwhiz To the first, perhaps; integrated amps do have the advantage that a passive volume control will work fine in them and there's no interconnect issue between the preamp and power amp sections. But often separates are built to a greater scale with less internal compromises.

To your second question, they don't need to be balanced but it helps, since the power supply is often the key compromise in an integrated amp. Balanced circuits impose less noise on their power supplies.

I followed up the idea in this thread - what happens when a good headphone amp is used as preamp in a speaker system. I have actually not tried this before in my main system. Or not since way back. So I brought Audiotailor Jade OTL down to the main listening room, disconnected the preamp, and connected Jade instead. The result was quite good, but not on the level of my (much more costly) preamp (Einstein The tube mk2). It would have been a sensation if it sounded better.

So my experience is that inserting a good tube preamp into the amplification chain depends on the quality of the rest of the gain stages in the chain. For example, the Jade easily beats small s-state amps in  active speakers, from my testing so far (low to mid price). But if the other gain stages are in fact of comparable or higher quality than the Jade, the effect can be zero, or reversed.

Note that, in my other systems, testing with the OTL headphone amp as part of the sound chain, the chain has been like this:

Source (DAC) - > Jade - > preamp -> amp.

In my main system, however, I had to connect this way;

Source (phono riaa + preamp) - > Jade - > amp.

I was not able to insert Jade as the first gain stage.

Something is wrong when it is connected as the last gain stage. I tap on a tube in Jade and hear scratching noise in the speakers. So the sound impression, described above, may be misleading. Maybe this isn't a fair playground for Jade. Connecting a headphone amp as the last gain stage, with output to the amps, is not the right way. Even if it works fine as the first gain stage.

Exactly my experience too...

Thanks..

So my experience is that inserting a good tube preamp into the amplification chain depends on the quality of the rest of the gain stages in the chain. For example, the Jade easily beats small s-state amps in  active speakers, from my testing so far (low to mid price). But if the other gain stages are in fact of comparable or higher quality than the Jade, the effect can be zero, or reversed

I have a headphone amp that is powerful enough to be a headphone amp or an integrated amp and power speakers. The Woo WA5.

As you are adding Build Your Own Amp's into the discussion, I feel you should be made aware of the Pass Designed Korg B1 Pre-Amp'.

I have referenced its usage on quite a few occasions within this forum. 

This is not a Phono Pre Amp, but personal experience of it in use with a Vinyl Source on a variety of systems has shown the Sources in use to have a presentation that has exceptional attraction.

The 4K , Audio-GD HE1 XLR....10 tubes, it’s own Regenerative Power supply. Sings with Any Amp I put it with... Simply a fantastic sounding PRE !     Caution:  It's a Monster.

@arhgef Having the same MC462 as you do, I will share some experiences. At first I was using a Fisher 400 CX-2 that I rebuilt. A wonderful sounding unit and possibly the best vintage preamplifier of all time. This combo created a nice vintage / tube undertone to my system.

The upgrade bug bit and after visiting the McIntosh factory, I stopped by Audio Classics in Vestal, NY and made a great deal on a new C22 MKIV and had it shipped to me in Florida. What a great combo! Some tube warmth, but a much more of a modern hi-fi sound. Unable to leave well enough alone, I wanted to see if the C22 would respond to some tube rolling. 

Much to my surprise, I could  hear subtle differences with every change I made. I finally settled on a Telefunken ECC801S for the output, a Telefunken ECC83 for the input, and Amperex 7025’s for the phono. The preamp was completely transformed  and I have found my audio nirvana.

I recently ordered a Moreplay preamp kit from Bottlehead to build for a second system and hope to have the same positive experience you did.

Thanks to all. Lots of good advice here. Further research and your posts confirm that a single ended pre in the chain certainly can make a positive difference. I like comparing vintage speakers and currently am using a B and W 803 matrix 2. The “sharpness” of that speaker maybe makes the tube a good choice. Will try to DIY a simple pre so that I can compare the effects of different tubes etc, and I think some of the reason a SET tube pre sounds good is the simplicity of the circuit, so this should be doable. A new adventure… Thanks and enjoy your music and systems.