Welcome to the VR forum!
Quite simply it was IMO the best sound I ever heard!!
but would the ease and beauty of what I heard in your room reveal that I would actually need the power of your monoblocks @75 watts a channel to be the main issue of providing that sound regardless that your solid state monoblocks and not my 22 watt SET amps are driving the Lumina L2's?
The Spatial Luminas are fairly sensitive (I believe around 95dB) and have powered-bass drivers. So 22 watts *should* be plenty in a 16x22 room.
I think it is everything else
about the preamplifer and power amplification that resulted in you hearing a much different sound.Let's start with the preamplifiers:
The L2 Signature Preamplifier is a significantly different design compared to the AirTight ATC2.
ATC2 is an SRPP (Series Regulated Push-Pull) topology and uses a 12AX7, a couple of 12AU7s (these are both 9-pin, indirectly heated tubes) and an Alps potentiometer volume control. I couldn't find more detail about it.
L2 Signature Preamplifier uses 4-pin directly heated triodes (stock tubes are 300B, and it is a 'convertible' design that accepts some other highly delicious sounding DHT's), is single-ended (no SRPP), no feedback, uses a discrete resistor volume control instead of an Alps potentiometer, and I am sure there are many other differences such as the very important power supply topology (L2 uses dual-mono, Belleson super-regulated power supplies), bandwidth, etc.
The L2 Preamp contains a unique circuit that truly sounds like no other (and with better quality DHT tubes than the stock 300B that was used at RMAF, it gets even better)! You are hearing the Directly Heated Triode (DHT) tubes do their thing, without being taxed by an output transformer or the load of a speaker (which is a significant load compared to driving the input of an amplifier) so you are hearing the DHTs in all their glory. And L2 is a very low-noise circuit (incredibly low noise for a DHT Preamp). L2 Preamp is by far my best preamplifier design, and I really don't know how I'll ever top it.
So the preamplifiers are going to sound completely different.As far as the power amplifiers:
Again, they are very different. Airtight 211 is an SET amp, has an output transformer, far less bandwidth (I believe it starts rolling off before 20kHz), an order of magnitude higher output impedance, lower output power (but as I mention above, it probably is still powerful enough for your Luminas because they are fairly sensitive).
L2 Siganture Monoblocks are MOSFET, significantly higher bandwidth, much lower output impedance, has greater than 3x the output power (and even more into lower impedance), etc. It's transient response is very impressive! It sounds unlike any solid-state amplifier that I have heard. Highly resolving, fast, musical - with only one pair of MOSFETs on the output. The amplifier board itself is very small, with low parts sound, short signal paths, and fed from very "good iron" (an excellent, custom-made transformer). And L2 Monoblocks by far my best amplifier design, and I really don't know how I'll ever top them either! (sure, wattage and size could be increased, but I'm talking about topping how they sound).
I am not saying one is "better" sounding than the other (of course this is matter of taste, and depends on synergy with speakers and other factors) - but they will sound very different.
And you were easily able to hear this at RMAF with the L2 Preamp and Monoblocks driving the Spatial Luminas (in a similar sized room to your own).
-- My approach with L2 is to let the L2 Preamplifier set the foundation of the sound with its no-feedback, directly-heated triode design, high bandwidth, low noise floor, etc. Then let the L2 Monoblocks "copy" that unique DHT magic and provide power gain to drive the speakers.
-- You were also
hearing the source (L2 Dac), which naturally plays an important role. It was running in non-oversampling mode, has a top-notch reclocking circuit, dual mono, Class A discrete output stages, and a whole lot of other tricks that make it a killer source.
So since you already own the Luminas, and you love how they sounded at RMAF, then feel free to email or call me about L2 whenever you are ready. The only two things that I would like to mention are:
1) Lead-time is getting longer by the week, as this is my busiest time of the year.
2) Starting 2019, there will be an increase to the pricing (I will begin taking on global distribution for L2). *Now* is the "pre-order" pricing of both components.
And thanks again for listening at RMAF and posting your impressions!