Help me decide on a new Little-Dot

I have a Little-Dot II+ that I bought in 2006 and a Little-Dot II++ that I got about a year after that.

The Little-Dot II+ uses EF92 Driver tubes and 4P1S (or 4P1L) Power tubes.  The power tubes are directly-heated pentodes operating as triodes.  The amp uses an iron core transformer.

The Little-Dot II++ uses EF92 Driver tubes and 6C19P Power tubes.  The power tubes are indirectly heated triodes.  The amp uses a toroidal transformer.

I bought the II++ mainly because it was offered as a discount to users who had bought a II+ after a flaw was found that would cause arcing in the 4P1S power tubes when the unit powers on.  The tube arcing issue ended up being mostly a non-issue over the 4 years I’ve owned the II+.

The II++ was marketed as being an improvement over the II+ and there are certainly some things it does better, but overall I always strongly preferred the II+.  The II++ has more bass, more kick, and more clarity, but when it comes to that groovy warm tube sound the II+ wipes the floor with it.  Electric guitars and vocals stand out as being particularly good on the II+. 

I figure that if I can identify why it is that I prefer the II+ over the II++ then it might help in selecting a new amp.

The models I’m mainly looking at are the Little-Dot MKII and MKIII.  The I+ looks promising also and I’m somewhat considering it (though I DO use my headphone amps as preamps fairly often and it would hurt to lose that functionality).  The Little-Dot MKIV looks nice but I’d prefer not to spend the extra money unless that is the only way I’m going to see an improvement over my existing units.  All of them have the capability of using my existing collection of EF92 tubes that i've gathered over the years so that is a nice bonus all around.

Given the difference between the II+ and II++ it’s obvious the huge difference power tubes can make.  It seems like I have a lot of different choices here in that regard.  The I+ doesn’t use power tubes so that is a bit of an oddball.  The MKII, MKIII, and MKIV all come with different stock power tubes yet most models have the option to upgrade to the better tubes.  I’m having a bit of trouble understanding what the difference would be between, for example, an MKIII and an MKII with upgraded tubes.  What is better about the MKIII and MKIV that makes them worth buying compared to simply getting a MKII and the best tubes possible?

My main headphones are my Beyerdynamic DT770-Pro/80ohm headphones, so it is somewhat important that whatever amp I get works well with 80ohm headphones.  I have heard that the MKII, MKIII, and MKIV are better suited toward higher impedance headphones but they are probably no worse at powering 80ohm headphones than my existing units.

I'd love to get a unit that has the amazing smooth tube sound of the II+ while also having the increased power and bass of the II++

bump

Quote:

Originally Posted by livewire 

If you are seeking power and clarity

Well, it's a bit interesting.  On my Little-Dot II+ it seems like the harder the amp is pressed the more tube-like it sounds, which is something I prefer.  I don't know if that is simply a limitation of the power supply or if that is a quality of directly-heated tubes (II+ is indirectly heated, and I believe the MK series is as well though I could be mistaken).  It has gain switches which are supposed to make it work better with low impedance headphones but I actually prefer to leave it at it's stock setting.   I would like it to have more power (bass mainly) but if that has to come at the expense of making it sound less tubey and more solid-state-like, then I suppose I can live without.  The bass on the II+ isn't actually that bad though the ++ is better.

So it's true that the new version of the MKIII can use the 6H30 tubes from the MKIV?

What other benefits would the MKIV have over an MKIII if both were using the same tubes?