Connecting your source directly to a power amplifier

[estreeter]

Hi All,
 
    I'm posting this here because I believe I may get more informed responses - many of you seem to have considerable experience with speaker rigs, and I expect that you have grappled with this exact issue. Steve Deckert piqued my interest by insisting that putting a preamp in the signal chain is rarely a good idea, and may actually give you worse sound than hooking your source directly to your amp. Integrated amps have a pre-amp side-by-side with the power amp, so (theoretically) they arent 'solving' the problem. Of course, his (power) amps all have volume controls ... 
 
   There are a couple of reasons why I would be hesitant to try this, but the main one is simple : fear of being instantly and permanently deafened. These are my concerns/observations:
 
    - the line-out on some sources is fixed and on others variable : adjusting the volume pot on the source may or may not alter the strength of the signal being received by your power amp. Whatever the spec sheet says, I would hate to find out otherwise the 'hard way'
 
    - even a passive line-stage (aka passive pre-amp, a complete oxymoron when its an attenuator not an amplifier) is still another potential gremlin in the signal path - if you can control volume at the source, do it
 
    - active pre-amps were designed to 'fix' low output sources like phono and early CDP - anything above 2V should be sufficient to drive a power amp - I dont know how well that works in practice.  
 
    Long story short, I can paste quotes on impedance matching and various opinions, but I'm interested in hearing from Head-Fiers who have actually been there and done it.
 
   - its interesting that every DAC manufacturer who offers a 'DAC/preamp' option charges handsomely for the addition of variable line control instead of building it into their base model DAC 
   - I read that Ravel's Bolero is an excellent track for assessing whether this is going to work or not, but my concern is that as soon as I hooked A to B and powered them up, the speakers would be damaged by the ensuing very loud hum of a signal with zero attenuation - anyone ?
   - yes, I can get some cheapo speakers for the initial hookup, but I cant get a new pair of ears - I guess I could just connect one little speaker and see how it goes ..... 
   - the Parasound 2125 is cheap enough that it would make a good candidate for testing without putting out 500w per channel. Have to wonder if a roadie has even been deafened at a gig setting up 1000WPC PA amps...... 
   
The obvious answer is 'stick to integrated amps, Junior, and leave power amps to real men', but I'm a curious type. Many people are still buying very expensive active preamps and the Pass Labs passive is long gone - am I missing something here ? All feedback welcome. 
 
Cheers,
 
estreeter
 
PS the Pass Labs Aleph L tech reportedly lives on at CI ..... 
http://www.ciaudio.com/products/PLC1MKII
 
No active line stage, no matter how good it is, will ever equal the sonics of your direct connection (or an equivalent passive).
 
http://www.high-endaudio.com/RC-Linestages.html

 

[mwilson]

Or this SPL volume control:
 
http://www.vintageking.com/SPL-Volume-2

 

[Mossback]

here is a staight wire with gain literally....with a remote.
 
http://www.placetteaudio.com/remote_control.htm
 
i used this product in my system (click on the audiogon link below) for 4 years as my volume control along with a custom switchbox. it is truely transparent if the cable lengths are sufficiently short. it is so transparent you can 'stack' 3 or 4 of these and it will sound the same as 1.
 
over 4 years i compared it to 7 or 8 $10k and up preamps and it was equal or better than any until i found my current preamp, the $30k darTZeel NHB-18NS.
 
it's the perfect analog volume control for single source systems.
 
and there is a 30 day free trial to make your decision risk-proof.
 
note; there are a few sources and amps that are not 'passive-friendly' but most are; hence the free trial.

 

[estreeter]

Thanks guys - greatly appreciated. 

 

[Clarkmc2]

Another very high fidelity solution. It didn't sound to my liking on my system, but it is top notch gear, from the master.
http://www.firstwatt.com/b1.html

 

[estreeter]

It's weird - I used to look at these and think 'Who would pay so much for a volume pot in a box ?'.  Its only when you realise how important it is to the end result that the penny drops - seeing the price of many active preamps also drives home how comparatively little a thousand dollars (!) is comparatively. Unlike a lot of high-end chicanery, this actually makes sense to me. Add the ability to change sources via a remote (on some models) and its looking more attractive all the time. 

 

[estreeter]

Quote:

i used this product in my system (click on the audiogon link below) for 4 years as my volume control along with a custom switchbox. it is truely transparent if the cable lengths are sufficiently short. it is so transparent you can 'stack' 3 or 4 of these and it will sound the same as 1.
 
Mike, I clicked on the link, but is that a home system or a showroom ? So much gear ! Anyway, kudos - my ambitions are considerably more modest. 

 

[obobskivich]

If an amplifier has a volume control on it, it has some form of attenuation. If that's a mechanical device (fader, pot, whatever) it's going to have issues unless it's some sort of unobtanium (they do exist, they're just expensive). Usually the mechanical pots and faders that you find on most equipment are cheap.
 
Some recent-ish mass-produced equipment actually still had quality mechanical pots (I'm looking at you Yamaha), but even those don't compare to what modern quality gear has moved to: IC controllers. Like these:
http://www.cirrus.com/en/products/volume_controls.html
 
Even the super-duper high end stuff is moving this way (Boulder is a prime example); consumer-level gear has been doing this for probably 15 years now. The reason is two-fold: it costs less than quality mechanical parts, and it's more reliable and consistent than mechanical parts. Oh, and if you have REALLY fancy implementations (like the Boulder, or Euphonix boards) you can have hundreds or thousands of steps (not that anyone really needs 1024 steps or something like that, but you can do it). 
 
As far as the impedance thing - check out the specs and abilities of your devices before you proceed. Many modern sources really can drive through a simple attenuator (of whatever variety) into an amp, but some cannot. Alternately, some amplifiers are super-duper sensitive and will be pushed into clipping as a result. Basically if you want to do the whole passive thing, go right ahead, just double check the numbers first - it will probably work, but there's always a fly in the ointment somewhere.
 
Regarding personal experience:
 
- I used to have a Sony ES CDP that could act as it's own preamp, and it didn't really improve/change anything. It was a neat feature though. I think there's a range of Pioneer Elite products (older ones) that did this better - iirc they had a CD player, power amp, and pre-amp that would let you bypass the preamp (through separate cable runs, not an internal bypass) and use the CDP's volume controls for "pure direct." I doubt it would do much of anything (the Sony ES straight into an amp wasn't any sort of improvement, and the loss of tone controls can be a bother for some users; you can always insert your EQ though). Still, it seems more "thought out" than the Sony.
 
- My new headphone amplifier set-up uses an IC volume controller in front of an amplifier, and honestly I'm tickled pink - no more cheap pots and cheap pot noise (and really I don't get why $50 computer speakers can have a stable pot but $600+ headphone amplifiers cannot). Tracking is very good too, which is the bigger thing you notice when you get away from cheap pots (in other words, the volume control doesn't act like a balance control due to being screwy). 
 
I'm a fan of quality volume controls, but let's not get carried away. ICs do the job and they're not mega expensive. I think you can get kits on eBay, or find a DtoA converter with a variable output (that's what I have). The only other solution I've seen for volume control (aside from ICs) that I really like, are the dual-mono controls that a lot of ESP amplifiers (and oddly enough, my tape deck) have. Each one can be as inaccurate as it likes (and it's not really inaccurate because it has nothing to reference to; it's mono), because you can dial them "flat" while you're listening (no it isn't as accurate as measuring it with a meter, but as long as one channel isn't noticeably louder than the other, it's likely within <1 dB) or you can adjust the balance without quieting one channel (or boosting the other). I do not want to imagine this solution for multi-channel though - six different knobs on one axle? No thank you. 

 

[estreeter]

@oboskovich, I sense that you may have come to Head-Fi from a pro audio/studio background - apologies if that isnt the case. I dont have any of the background - I just staggered into Head-Fi looking for a decent set of cans. Along the way, we are exposed to a wide range of opinions and recommendations, but I rarely see a chip recommended over an analog alternative. 
 
I'm a simple soul, but I look at Benchmark's pricing for each version of their DAC1 and I ask myself 'are they adding functionality I can use, or simply adding more potential noise in the same casing ?'
 
DAC1 - 1K
DAC1 USB - 1.3K
DAC1 PRE - 1.6K
DAC1 HDR - 1,9K
 
Granted, the HDR is the whole enchilada with a remote control, but suddenly I'm paying almost double over the cost of the base model AND I'm gambling on the fact that I will enjoy the USB implementation and the preamp functionality as much as the highly recommended DAC. This is where a little voice in my head says 'Get a pair of active speakers and a decent interconnect and ignore the amp fetish'. Even the passive buffer idea suddenly seems needlessly complicated, 
 
Inevitably, I'm missing something here, but thats OK - I've got months to sort this out.   

 

[obobskivich]

I don't know much about the differences between the DAC1 units - got a link? (I'm just curious).
 
The thing with IC controllers is mostly a desire to have things work "right" and be sustainable over time. If you like mechanical gadgets, stepped attenuators and super high end ganged pots are always an option. I just think they're really expensive for what they accomplish (and it's all labor, it's not an overt scam - if you've got a guy sitting there building a rotary switch or something with  high-precision parts and so on, that takes time and costs money). 
 
You mention active monitors - what are you trying to build? A listening room? Near-field setup? 

 

[pyramid6]

If you want tubes in the path, sometimes a pre-amp is the only option.  In my case, my pre-amp will be my headphone amp.  I can add speakers and not have to switch cables around.
 
Computer -> DAC -> Pre-amp/headphone -> Power amp
 
My DAC has volume control so I could skip the pre-amp, but then I wouldn't have lovely tubes.
 
I don't think there is one right answer.

 

[estreeter]

Firstly, please be aware that this isnt the usual 'I gotta order something tonite !' situation - I want to do this once and do it right. I am perfectly happy to keep listening via phones for now.  
 
Its just a simple nearfield desktop rig - supposedly 'simple as'.  Focus is on a networked streaming device for the source, a decent DAC and a reasonable pair of monitors. Where is gets interesting is when I try to balance my interest in various amps, including vintage receivers, against a fervent desire to avoid the rats nest of power cords and cables which would inevitably follow. Headphone rigs are so simple by comparison - I could hide my current DAC and amp *under* a desk and need exactly *two* power outlets - one for the computer and one for the headphone amp. Add some networking gear and its maybe 4 outlets. Heaven. 
 
If we ignore the shifting goalposts around the digital source - a domain that is getting better all the time, btw - and accept that there are plenty of DACs out there (!), I can easily see myself ending up with two speaker rigs. Ignore everything but the desktop, and picture an iMac with a pair of monitors either side of the computer screen - like I said, simple. This is a rough shortlist of the active monitors I am considering:
 
$600-800 :      KRK Rokit 8, Genelec 6010A
$1000-1300 :  Mackie HR624 Mk 2, Genelec 8020B, Dynaudio BM5A MKII
$1600-1800:   Mackie HR824 Mk2, Genelec 8030A, Adam A7X
 
My speaker budget is around 2K, but where I found myself sliding into a hole was when I tried to accommodate everything in my initial overall plan. I can easily see how people end up with several rigs. Cleanest approach for me is to forget the amps on the desktop - even a T-amp needs a power cord and cabling. Of course, that raises the issue of 'where do I plug my headphones in', but there are a number of DACs with a headphone amp built in - again, the simplest and cleanest solution. Is it 'the best ever' ? Probably not, but we've all seen photos of those rigs ... scary. .. 
 
Sonically, I dont know if studio monitors will be too ruthless for my music (mostly guitar-based rock and very little classical), but I know from past experience that just opting for a pair of bookshelves from Dali or similar on the basis that its 'only a desktop rig' will underwhelm me. I know nothing about the actives beyond what I have read, and I'd be willing to buy the two cheapest options above (with a view to finding a sound I like in at least one pair - use the other with my PS3) over a single more expensive speaker that lays everything bare in the production (I suspect that would be the 8030A). Not looking for a sonic microscope at that end of the chain, Hell, I dont even need a lot of volume, particularly now that I've mentally moved all that other gear into the living room  

 
Anyway, I have plenty of time to nail down exactly what will go where - just happy to have reconciled the whole vintage receiver/modern amp thing in my tiny mind. That can wait for later. I spend too many hours in front of a computer screen to be messing around endlessly. 
 
Rough breakdown of my current budget is - 1K for networked source -> 1K for DAC -> 2K speakers and no more than $500 for whatever cabling I need. All up, if I spend more than 5K USD on the desktop rig, it will leave me less for beer and DVDs. Music is important, but I dont spend 18 hours a day just listening to music. 

 
Just a nice, simple mid-fi rig - what could be easier, right ? Right....   
 
PS The Benchmark gear can be found here:
 
http://www.benchmarkmedia.com/

 

[Mossback]

Quote:

Mike, I clicked on the link, but is that a home system or a showroom ? So much gear ! Anyway, kudos - my ambitions are considerably more modest.

 
it is my home system, built in a barn. and thanks.

 

[Currawong]

I demoed a Linn Klimax Twin straight from an iBasso DX100 and shocked the salesman with the result. Very likely, as I only use computer-based audio, if I were to set up a regular hi-fi system it'd be with a DAC/pre and power amp.

 

[estreeter]

Quote:

If you want tubes in the path, sometimes a pre-amp is the only option.  In my case, my pre-amp will be my headphone amp.  I can add speakers and not have to switch cables around.
 
Computer -> DAC -> Pre-amp/headphone -> Power amp
 
My DAC has volume control so I could skip the pre-amp, but then I wouldn't have lovely tubes.
 
I don't think there is one right answer.

 
 
Agree on several points here, but I have ruled out hot tubes anywhere on my desktop. I know others do it, and seem to survive the experience, but for me its not an option. Note that with at least one of the passive controller options above, not only would you never have to swap cables around, you wouldnt even have to touch a single volume pot manually. The 'preamp as headphone amp' is a fairly well trodden path, and its something I alluded to in the post below this - the difference being that something like the 'non-pre' versions of the DAC1 dont need preamp functionality to drive active speakers. I know I've veered slightly (!) off my own topic here, but its all with the same aim - minimise the amount of gear I need to buy, particularly costly cables.