Looking for an amp that punches way about its weight and I can grow with

+1 for Rogue. I only have experience with their RP-1 pre But I like it. It does not have XLR but it performs as well when I used my DAC/pre with XLR. Good outfit to work with, but you will have to determine if you want to try their amplification.

You can also do a buy and try with PS Audio products. They are also a good company to deal with. I had their S300 amplifier for years and it ran flawlessly and support was good. I have toured their facility and it’s a first rate operation.

The Bryston cubed series is another suggestion. I have never experienced their amplification but have other products from them and their warranty on new products is like 20 years and they are another good outfit to work with.

always have a fire extinguisher available and wear fire retardant underwear when listening to mcintosh gear...  

LOL there was this big puff of pink smoke that came out too.  I am pretty sure I didn't imagine that but....I cant say with 100% certainty.

After owning some Mcintosh products, talking to support and having a short conversation with a rep at a store demo. I'm not sure if I will ever purchase any of their gear again.

Unfortunately I have found that there is an invariable positive correlation between weight and high sound quality. 

tubes4hifi amplifier KITs page

I don't know how your speakers respond to tubes but these are powerful enough to push them. And they are in your budget. They come in kit and completed form. I bought the ST70 from Bob just to dabble with tubes and the amp stayed in the system for 10 yrs replacing a high $$ SS amp. Customer service was/is top notch as well. I now have Don Sachs Custom version of Bob's ST120. It too may push your speakers. But it is above your budget at $4k

@Op  I have McInosh amp and preamp.  Recently I have shopped for sources (DAC and phono) and prior to a scheduled auditioned hear the sources go through Rogue and Moon by Simaudio. 

I think both are a great value for the price and when it comes to me upgrading I will be auditioning Moon with McIntosh and Rogue maybe Audio Research or VTL depending on my willingness to spend

I bought a new McIntosh amp over the phone from an authorised dealer a few years ago..I paid shipping but not sales tax because i was out of state(no dealers within 500 miles of me).When i sent in the warranty info,it was sent back to me denied.Their reason was according to their warranty" if a product is not purchased at the store and sales tax collected no warranty exist".I talked to i dont know how many at McIntosh,got no where and the dealer was basically no help The MC402 was sold a year later and i didnt need the warranty but i swore that was the last time Mcintosh ever got my money.The amp sucked and i was glad to get rid of it......good riddens McIntosh you blow. 

https://www.usaudiomart.com/details/649443660-magnus-audio-ma360/

ML's and tubes sound lovely. I tried my Quicksilver Mono 60s with them and they were great; QS Mono 120's would be good, too, and I've heard a lot of love for Aric Audio, too. Supratek is on my short list, but Australia is a long way away.

Purchase used PASS 250.8 ASAP!!

I would suggest Pass as well however your budget may get you an X250 and perhaps stretch to an X250.5 a 250.8 is out of the question for $3K.

Pass Labs service and support is excellent.

Chuck   

Will look at the Pass Labs stuff.  The 250.8 is WAY out of my budget.  Have to find a good source of used sales for them.

You may want to peruse US Audio Mart as well Audiogon. https://www.usaudiomart.com/

Why on earth do members suggest (with exclamation points, even) gear that is more than double the stated budget of the OP? [FFS: https://www.hifishark.com/search?q=PASS+250.8] How is that anything more than huge time suck? Why is it SO important to blurt one’s preference onto a forum? Think it makes others impressed? Not. At. All. 

I think you should be able to buy an Aesthetix atlas for a bit over your budget.

I owned one and it was 100% reliable, built like a tank, and will drive anything.

Check it out. Highly recommended.

"...ML's and tubes sound lovely. I tried my Quicksilver Mono 60s with them and they were great; QS Mono 120's would be good..."

The ML Electromotion ESLs are not that hard to drive and I have driven mine quite well with QS Mini Monos, AES six pacs, a Prima Luna integrated (using that now), and also a big Mac MC402. The tubes are the best, the MLs are toward the bright side so an all tube setup really works well. For you the best budget system would be your Shitt pre and a pair of QS 60 watt Monos. Add a sub and you'll be happy for a long time. 

LOL there was this big puff of pink smoke that came out too. I am pretty sure I didn't imagine that but....I cant say with 100% certainty.

Well it is Pride Month, just sayin...............

AGD Audion mono blocks. Unlike any amp I have heard. 170 watts into 4 ohms 85 into 8. They are so transparent, distortion free, detailed and liquid they punch way high. Maybe best there is regardless of price. Comes with a long trial period. I did not hear of anyone sending them back. They are the sweet spot in the line but I may return mine for the top line Gran Vivaces. Worth a call to Mike Powell Audio.

tvad

It was a transition process for me moving away from decades of 300B and 45 SETs. First I had to focus on why so many love their SS. Ultimately, my understanding of SS sounding like or better than SET concluded that there was, at that time, only one SS amp that satisfies me-Bakoon. I bought a Bakoon headphone amp. It is not “warm” and “delicious” like my SET but, as you said, has qualities well beyond tubes and SETs. Mostly, the lack of distortion and way more detail made me not miss my SET. Granted, this came with the mentioned transition away from SET and toward SS. It took time to accept and appreciate the “open window” quality of the Bakoon and not miss the beautiful but distorted SET. If you love SETs it is called warm if you appreciate SS it is distortion. 
Well after Bakoon, I discovered AGD. The AGDs are as much or more “open window” as Bakoon with much more power, mono blocks and balanced. And the AGDs reveal the most subtle and profound beyond Bakoon and SET… musician’s phrasing. When hearing the beginning, ending and nuanced presentation, the whole thing leaps toward realism. Bakoons are mentioned in 2 reviews of AGD. They are wonderful but AGD is another story.

In your price range the Parasound Halo 21+ should fit the bill. 300 wpc into 8 ohms and 500 wpc into 4 ohms. Save up over the next few years and buy a second. You can make them 1000 wpc mono blocks. Can't go wrong w/John Curl designs.

Raven says his will drive them no prob. Order one and see.

tvad
Thanks for your thoughtful response.
Moving away from a beloved SET is, perhaps in your case running all AN, a move too far.
Certainly, your excellent amp and perfect speaker match must produce a joyful sound.
My speakers need and love more power.
My 300Bs pushed them well but I discovered a new world with the AGDs. I see that your world is very full of the strengths of SET.

I just hit my 50th with Mcintosh this month. The newest piece I have is a C2500. I blew it up. Cable drop!! High pitched noise and knocked out a MC275 doing highs a VTL MB doing mids.  A month later the C2500 lost the same channel as the cable drop. 15k if you just replace gear.

BTW the Nords doing bass duty Class Ds is where the single right cable DROPED and lay while pounding away.. The class d NEVER stopped playing.. Active XO was the reason for the total blunder. THAT will never happen again. I shrink tube AFTER I torque speaker terminals. NOW!!

The VTLs cost more to fix than buy on a fair used market. Bummer

The MC275, with a NEW transformer and PS check/rebuild, two caps and 3 resistors. 1200.00. GG  CE, it has logic boards.  I went ahead and replaced ALL the caps with Mundof whites. 35.00 more. Works perfect!

The C2500 300.00 for a bias repair. Works perfect!

It's reasonable to KEEP Mcintosh.. VERY cost effective to repair and maintain..

ALL the repairs were done at a authorized dealer in Citrus Heights CA.. 6 weeks..

The other 35 pieces of Mac gear.  :-) What can I say, jealousy ALWAYS brings unkind words..

BUT I am reading a few out of the box failures that I just never heard about before. Last 5 year more so..

I'd stick with Mac, but for 3K, I'm not sure there is a 3K Mac SS amp.
Good Class Ds yea... No problem for 3k.. Nord for one.. I'm using a pair right now with small planars.. Wonderfully COOL.. and good SQ..

All Mac, Decware, Thoren, frontend and source with Nord/Mac/Cary for power amps .. GR OB servo subs and Behringer, bass and Mid-bass management.. 

Regards

What sound characteristics are most important to you?

I'm using PrimaLuna amps with my Ethos MLs  and they sound great

"Space-Tech Laboratory - High-End Audio" http://www.thebestamp.com/Hybrid_Power_Amps/SA-700.php




"Space-Tech Laboratory Ltd.'s Feedback Summary - Canuck Audio Mart" https://www.canuckaudiomart.com/userfeedback.php?user_id=24170

I would try a parasound amplifier in that price range as well, the a21+ would be a good choice for a martin logan, but you may want an all solid state pre amp with it because they do not mesh with tube pres at all.

If you want tubes you can't go wrong with either Rogue or QS. Biamping MLs with tubes for the panels and SS for the bass will greatly improve SQ, especially the bottom end.

My particular model of MLs can’t be biamped I think I need to go up a model or two before that is an option.

I think Odyssey is a great choice. What Klaus would build for you is for your system, your needs, and your preferences. It is not a “one size fits all” operation. He takes great care to understand your needs and builds the amps for you. Stratos monoblocks are about $2700, so are within your budget, but he can also do a stereo amp. The beauty is how they can grow and change with you. Upgrades are abound with hundreds of different combinations as your tastes or system changes. Odyssey also likes tubes, so your Freya should fit right in. Plenty of power for Martin Logans. I paired my Stratos’ with Magnepan 1.6’s until I got his Odyssey Kismet Reference monitors.
Give him a call! A conversation is free.

Second the Odyssey recommendation. I have a new Kismet amplifier in a Stratos case from Odyssey, paired it with a Hegel preamp, and am really enjoying it. 

@tvad how did the LTAs stack up against the others. You’ve tried some interesting amps.

$3k Simaudio 340ix.

@OP I am not familiar with the impedance and sensitivity of your current speakers or Martin Logans. But I would say if your budget is approximately $3K for the amp it would be good to know if you plan to only use high sensitivity speakers or not because that will impact the wattage you will need to some degree. More so with SS than with tubes. As far as Pass Labs I think they are generally going to be beyond your budget especially if your wattage need is high. I even think a Bryston 4B3, which is a great amp, might be beyond your budget unless their used market value has dropped. For keeping within budget you will definitely make it with a pair of Schiit Aegirs or Vidars used as monoblocks. But not sure they meet the punch above their weight criteria.  Maybe. But, and this maybe controversial for some of us here, I think you can find something within your budget, that will represent good value, and if purchased through a reputable company or it’s US distributor, if you look to a Chinese company. Contrary to some opinions here, and political issues aside, companies like Denafrips, Keces, Holo Audio and others who I am not recalling make quality products. I own some of them. If they make amplifiers I would check them out. But, as I have said on other posts, no matter who the company is, always try to pay with a credit card that values your business and has excellent buyer representation when disputing a charge. Use that card through PayPal so your card info is protected. IMO the best card to use per the above is American Express. Since I don’t think you are interested in active speakers I will leave it at that. I hope that was helpful. 

+1 @jperry for the Aesthetix Atlas. Superb hybrid amp. Best part is that you can send it in to get upgraded at any time as funds allow. A great long term buy. 

The Esl and esl x are great speakers! I had the esl x and eventually upgraded to the esl 13a. Here is my opinion.. ML speakers love power... but not just watts, they also need volts. 
Do yourself a favor and read this:
http://sanderssoundsystems.com/technical-white-papers/52-esl-amp-white-paper

I have the magtech amp and it’s totally badass. Im not saying that its the one for you but I promise that high voltage is super important. 
Maybe demo a t+a amp 8 as it is a hv design... or just pony up for the magtech 

They are both very extended and transparent. Deep resolving bass Smooth. Grain free highs. Exceptionally quiet. Large image. I thought the ZOTL40 with its EL34 tubes had a little more forward midrange “bloom”.

I thought they lacked some “flesh on the bones” if that makes sense.

sidebar comment and response to @tvad's post above

i also have the lta zotl40 ref - the amp is definitely among the most transparent, 'insightful' tube amps out there... certainly the most transparent i have heard and i have had many many of them... the degree of midrange and midbass bloom from that amp can be improved by using mullard old stock el34's or (their close equivalents) and careful selection of input tubes

BRYSTON and PASS LABS both made incredible amps that are built like tanks and will last as long as you wish them to. They are expensive, but at least in this case you will get every penny's worth. These are both products that simply don't decay with age. Either one will drive the Martin Logan's to their fullest sonic capability. I have heard both. The fact that you are a heavy rock listener makes me hesitate to recommend any tube amps. Most "Rock Guys" don't care for the sound of tubes.
But if I were, it would be PRIMA LUNA EV400'S with the EVO400 preamp. The key to "rock" in this case would be to load the EVO400 with a full set of TUNG SOL KT150's. I believe it would change your mind about tubes very quickly.

Ditto on the Bob Latino VTA-120 amp. With good coupling capacitors and a good rectifier, It's really excellent. Very wide top end. And, if you've got efficient speakers, you can switch into triode mode for that rich mid-range sound.

Check out the ModWright KWA 100SE Power Amp. (I own one)
It works well with a tubed front end.

One word: Carver, the original Bob Carver - made amp.
The formidable but light weight PM 2.0 produces an easy 460 W/channel full range, delivers massive well damped bass and musical and natural mids and highs. It has been a reliable pro amp for touring rock bands and I use one at home in the bass channel of a bi-amped system, as well as  half dozen of these for the bass channels of my large tri-amped pro systems. (stagersound.com).

Back in day 1978 I own MAC gear C28 Preamp & the 2105 Power amp very dark & veil, not a happy camper. In fact the only MAC gear I like is the vintage tuners which I now own the MAC MR 73 I like a dark tuner. I sold the MAC gear for Dynaco gear which was half the price and sound twice or more better. I`ve gone through quite a few amps in my day; eventually I sat in at a PASS LABS listening session it was all over found the perfect mate for my 3.6 MAGGIES the Pass XP30 Preamp & the pass X350 Power amp. I was thinking about a Pass 350.8 however, this 15yr old tank sounds good I think I`ll just have it recapped and enjoy another 15yrs. BTW there`s a used new to you X250 on usaudiomart.com #345 for sale $$ your budget can`t go wrong with PASS the ML`s will stand up and sing Oh happy day Oh happy day when PASS came into my life who ray who ray!!

Van Alstine. I just bought one of Frank’s used solid-state amps from his website. 30 day trial and 1 year warranty. It’s a keeper. You have options here for your 3k, new or used. I Could not be more pleased. Great amp for the money, and very tube-like sound, and I have had tubes for a long time.