Philips SQ E188CC 7308 Preamp Tubes Matched Pair - Miniwatt - Holland 1965 - NOS

Immediately appealing is the super smooth highs offered by these tubes with lots of open air. The overall tonality of SQ is warm, musical and euphonic. The midrange displays some secondary octave nuances, which is very unique and can hardly be found even among the top-end German tubes. Similar to the Telefunken tubes, the SQ's can create infinite levels of harmonic depth and a liquid sonic texture without altering the musicality of the sound. The bass on these is the clear winner of the Heerlen tubes family: articulate, accurate, deep, textured, full-bodied and powerful. The sound stage is wide and structured - it feels the dimensions of the sound shape are clearly defined no matter how it moves.  

Vocal representation on these is close to Mitcham and Blackburn Mullard tubes in terms of warmth, sweetness and texture, making them great alternatives to Mullard's as the best vocals tube. But what truly shines on SQ E188CC tubes, especially the early '60s version like this pair, is their magic in portraying piano music: creamy smooth, richly colored, realistic and intimate. For many audiophiles (incl. myself), they're the go-to tube for piano sound. Listening to Claudio Arrau's Beethoven Complete Piano Sonatas on these tubes should be on your bucket list if you are into classical piano music. 

The ultra low noise on SQ's also sets them apart from most of the high-end tubes. They don't just compete with Telefunken tubes in low noise; they're known for being a long-term leader in low noise. As a result, you get superb detail and clarity from these tubes as well.