I found this and it looks pretty good

[[url=http://[/URL]="http://www.mackie.c…"]Mackie - Big Knob[/]="http://www.mackie.c…"]Mackie - Big Knob[/]

Anyone who can recommend it?

Not sure about the current model, but I've heard of people having issues with the Big Knob.

Since I switch between two sets of monitors, I recently purchased an [[url=http://[/URL]="http://pro-audio.mu…"]SM Pro M-Patch 2[/]="http://pro-audio.mu…"]SM Pro M-Patch 2[/].
So far I am loving it. Previously I had used the optional MSR for my Presonus Firestudio.
The SMP has all the same features of the MSR, minus talkback and the potential to do 5.1 mixing.
Since I wanted the ability to monitor in mono at times, switch between two outs (monitors), and do so passively, this was the right buy for me.

What DAW and interface do you use? There may be a better way to handle your need for headphone outs as well, but I need to know your setup - you may be able to set up different mixes for you, and each musician. A very handy thing if you can do it.

The HP-4 is about the only one that puts it all in ONE device. You can get active or passive monitor attenuation in a few devices. But not normally in combination with a headphone preamp. The HP-4 isn't anything great. And it is kind of sub par for a headphone preamp. I have a samson Q5 and it's junk too, but as a headphone preamp it has a lot of umphhh. A lot more than my HP-4. Pretty much anything less than 25% or greater than 50% on the HP-4's volume sounds bad. Fortunately the cheap PC speakers I plug into mine have their own volume knobs so I can find a happy medium most times. I got it mainly for the active monitor attenuation. And the mute button. Telephones, feedback, and other annoyances that that little button can save a lot of grief on.

It depends on your budget, but if you look for talk back devices, they normally include some of that functionality. Albeit on the pricier end of the spectrum. Not that I have or have used any of these, but...

JBL MSC1
KRK Ergo

And probably dozen of others if I were to keep on googling.

In the real studio world, back in the day, we never had " headphone amplifiers". A headphone amplifier is only good when you're sitting in your bedroom control room with a couple of friends sitting next to you. Which is what most folks here are doing. So disposable headphone amplifiers are, well, disposable headphone amplifiers, which you shouldn't spend a lot of money on since they are just, er, disposable headphone amplifiers.

In the big studios, you frequently had to distribute headphones to 10 to 20 or more people. Those generally meant that we utilized some big ass amplifiers just like our control room speakers were on. Well, maybe not quite that powerful. We then created " headphone boxes". These were generally passive homebrew boxes with a couple of resisters in them along with a volume control and perhaps a switch. And you never used shielded microphone like cabling. That's because most amplifiers don't want to load its output to a inductive load. So you use standard unshielded ZIP cord or electrical wiring. Now that's a headphone system for studio applications. Brute force & quantity. Of course the resisters we selected for our headphone boxes were to keep the headphones from blowing out and keep you from going deaf. I'm really not sure why someone hasn't released some kind of studio headphone distribution kit to be utilized with your favorite surplus stereo power amplifier? You'd think a company making headphones would release something like this? Then they could sell you more headphones. And he should never have more than one good pair of reference quality headphones, for yourself. For everyone else? There's MasterCard headphones or should I say, quantity over quality, since they're going to get beat up, beat to death, stepped on all the time. So in the studio you need cheap but loud, sealed over the ear headphones. Like those 5 for $100 Sennheiser's. Whatever you get, buy them by the bag.

A good headphone system is in the bag
Mx. Remy Ann David

The Q5 kind of fits that in studio usage. Passive pass through for the monitors so you can daisy chain them for quite the run. TRS ins and TRS outs. And a mono button. Kind of need the mono button these days, not so much for the mix as it is to give the gal in the vocal booth the option to mix the band (L) and herself (R) into her phones (or whatever setup you went with).

The Q5 is not of much use in terms of adjusting a stereo pair of near field monitors though. Which is the one feature of the HP4 that let me know that I needed it as soon as I saw it up for sale on craigslist. What's that? Hey, that's something I could use. The headphone outs lets me check the mix on more cheap-ish speakers. Ordering one new since all of the CL bounty was gobbled up quicker than I could hit reply, was a whole other adventure.

I was actually in a studio as a client with my college jazz band back in the 80's. Late 80's, but still. I hear you on the DIY box, and going deaf part. No knob, just all loud all the time. Which generally meant having the phones off ear. Over temple, around neck, and other probably shouldn't have even plugged them in to start with attributes. Not very problematic as a loud group / individual (trombone). But I would hate to have been a singer or something. Which we had at that session. Perhaps that's why they were always screaming.

Talk Back, Monitor attenuation, and headphone preamp rarely reside in the same singular device. Outside of a full fledged mixing board 24+ channels and all that jazz. But they do exist. At least these days. Although talk back might be a Walkie Talkie or baby monitor for a lot of folks. And monitor attenuation some DIY box. Although the Big knob and other variants exist as well.

Presonus central station was the one that I was originally trying to find. With the CSR1 to bring the action closer to home. That's a bit pricier than I thought.