which tubes for which genre ?

i have finally decided to turn to tubes but have no idea where to start, i've been reading into 2a3 and 300b triodes but they seem to have a reputation to shine in accoustic and vocals. i mainly listen to rock do these tubes do well in rock or am i better off looking elsewhere? i use the dynaudio audience 42's
the dynaudio likes rock, and likes power too
2a3 and 300b triode output tubes used in single ended fashion perform their magic typically on female vocals and small acoustic groups. They are low powered, and require the use special high sensitivity speakers which also should present a high impedance (typically 8 ohms or more)load. You would probably be best served by a "push-pull" tube design. You don't state your budget, but a good starting place would be something on the order of a Dynaco Stereo 70, or one of its clones, (I believe some of the newer models put out 120 watts/channel) which would drive your speakers quite nicely in a medium or smaller room, provided that you are not looking for "headbanging" sound levels. If your budget can stretch higher, Atma-Sphere, Audio Research, Conrad Johnson, to name a few, are brands to have a look at. Please remember that tubed gear requires some maintainance which can be a pain in the A--, and can be costly, so consider the price of retubing, along with the difficulty in setting bias voltages (if needed) when making your decision. One other thing, tube amps can generate a lot of heat, nice in the winter, but not so nice in the summer. FWIW, IMHO, if you just want to get started into tubes. . .The Dyna's are, and have been for quite some time, hard to beat at their price points. If you don't like it, you should have little or no trouble reselling. Happy Listening
For what you're interested in, SETs might not be the way to go.

Do some research on push-pull designs which should give you the power to rock out. KT-88 based designs could get you there.

Another option is using a tube preamp with an SS amp.

Good luck!
I have to agree that SET amps will not satisfy you playing rock music. There are some with higher power outputs that MAY work with an 86db speaker, but- most tube amps output less into 4 ohms than 8(the audience is a nominal 4 ohm load). You could get away with 40-50 push/pull tube watts, if you're not into rocking the house(like a pair of modded Dynaco ST-70's switched to mono). There are some good hybrid amps(tube driver/MOSFET output) available on the used market that would give you the option of trying different tubes, but would still have plenty of solid bass and over 100 watts per channel. An excellent example with 250wpc: (http://www.audiogon.com/cgi-bin/cls.pl?ampstube&1230558327&/Audio-By-Van-Alstine-Fet-Valve-Ultra-550)
Your speakers are the limiting factor, not the SET amp.

Make no mistake, DHT Flea Powered SET amps, be it 2A3/45/300B/171A/845 etc. can do rock and can do it very well. They can give you details like you have an electrostat speakers, and tranparency like a ribbon base speakers with bass as if you have enormous stereo subs in your room provided that your speakers can produce them and have the right sensitivity.

In short, yes, SET's can rock! The question is, can your speakers handle low powered SET's and do them justice?
Waste of money pal especially for rock...
And What's the point havin' amp only for voice or small acoustic bands???
Anyways, one of my favorite tubes are AudioResearch VT100 and I like it with any type of music. It can rock, sing and jazz, just give it the right speaker -- yours are but there's always room for better match...
Also you can research VTLs and Quicksilvers that are more affordable options
Matter of fact: A pair of VTL 300 Monoblocks would be a perfect match for your speakers(if you have the room). Whatever load they are wired for will receive their full rated output. Just be certain they are internally connected for a 4 ohm speaker(easy). WON'T break the bank/WILL rock the house! Very fast slew rate for a tube amp(more detail/accuracy, better imaging, great soundstage) and excellent bottom end.
thanks for the advice guys, let me start from the beginning do the audience 42's match better with ss or tubes ?
For rock, I would recommend KT88's in push pull.

This will give an easy 30+ watts clean.

KT88's give a very linear uncolored sound.

John C.
I agree that a higher powered push pull amp like vtl,manley
audio research,quicksilver and cary would be my choice for this speaker;but if you can $$ a atmasphere ma1 or ma2 I would look at those as well.
If you able to audition amps in your area I would listen to all that you can; how big your room is will be a important factor as well.
What amp do you currently use to drive the Dynaudios? I share the skepticism of some who have posted responses to you -- if you want to rock, I don't see why you're thinking of tubes. I've owned a variety of tube amps and preamps -- Conrad-Johnson, Quicksilver, Primaluna, Audio Research, Eastern Electric, etc. They all had their attractions, but since picking up a Naim Nait 5i integrated a few years ago, I've had no desire to go back to tubes (which can demand a lot of care and feeding, esp the power amps). But I have a small room and mainly listen to jazz and classical, not rock, so your experience may vary. I still think it's worth thinking twice about WHY you want to go tube -- what goal are you trying to achieve? There may be a better means to the end you seek.
Just to follow up on my previous post -- if you are a complete newbie to tubes, and you just want to try them (a perfectly reasonable desire), then you might want to go with an integrated like the Primaluna Prologue 2. It's pretty much plug-and-play, with its auto-bias feature. And it allows you to use various power tubes, so you can compare, for example, KT-88s and EL-34s. You can do a little tube rolling with the small tubes as well to tailor the sound to your liking. I owned the Primaluna for a while and liked it, and unlike some other tube gear I've owned, it always behaved well, never needed fixing.

Another possible combination for you -- a tube preamp and a solid-state power amp. One of my favorite combos from the past was a Conrad-Johnson PV12L tube preamp driving a McCormack DNA-125 power amp -- grace, warmth, and muscle.
15465550, the Audience 42 is built for transistor amps in an attempt to get more power into the speaker without affecting its apparent sensitivity. But the speaker can be driven successfully with tubes, and while you will need some power, you do not need a power house amplifier- much more than 150 watts and you can damage the speaker.

I would recommend something that has at least 60 watts or so. Some tube amps will drive the speaker very well directly, but IME many tube amps do have troubles with 4 ohms, so my recommendation is to also consider using a set of ZEROs (see http://www.zeroimpedance.com).

If you do this properly, you will find the bass of a good tube amp to be actually better than that of most transistor amps.
Just before Ralph (Atmasphere) chimed in I was in the process of recommending his amps (Atma-sphere) for the Dyns and those that want to rock with tubes. The 60 watts the M60 pushes with the zeros to raise impedance would do justice to the Audience 42's and most dynamic driver speakers. Despite Ralph's comments I would say add a good sub because of the small woofers in the 42's and rock the joint.

I am driving ACI Jaguar 2000's with M60 v.III amps with great satisfaction. The Jaguars have Dynaudio drivers but the Atma-sphere amps have never blinked. Bass below 70hZ is handled by an ACI Titan sub.

Entrope (the other Ralph)
your dynaudio speakers are great allrounders...i wouldn't be afraid the pair them with any good push/pull tube or ss amp.