SGAMBATI AND MARTUCCI
Most of the composers mentioned in post # 1 were infact also composers of operas. Giovanni Sgambati and Giuseppe Martucci, on the contrary, never wrote for that genre. They promoted new music institutions in Italy and organized performances of German music: the Dante-Symphonie and Tristan und Isolde were premiered in Italy under the direction of Sgambati and Martucci respectively.
"Sgambati has composed two quintets which I consider the most remarkable works of this kind to have appeared in many a year" wrote Liszt in a letter from Rome and surely you should try them as well as Martucci's one. Their orchestral works are not many: for a first approach I would put aside the first Symphony of Sgambati and the first Piano Concerto of Martucci and enjoy the works posted here.
The Requiem probably deserves a second recording but in the meanwhile you can take this one:
Giovanni Sgambati (1841-1914)
Messa da Requiem
Joern Wilsing baritone
Philharmonischer Chor Heilbronn
Members of the Staatorchester Stuttgart
Ulrich Walddörfer
Carus 83.121 (1991)
[flac, cue, log, scans]
Courtesy of Nozomi
Giovanni Sgambati
Symphony No. 2
Piano Concerto Op. 15
Martina Filjak piano
Orchestra Sinfonica di Milano Giuseppe Verdi
Francesco Attardi
Amadeus AM 304-2 (2015)
[flac, cue, log, scans]
Giovanni Sgambati
Piano Quintets Nos. 1 & 2
String Quartets Nos. 1 & 2
Roberto Plano piano
Quartetto Noferini
Brilliant Classics 94813 (2015)
[flac, cue, log, scans]
Giuseppe Martucci (1856-1909)
Piano Concerto No. 2, Op. 66
Orchestral pieces Op. 55 Nos. 1-2, Op. 61 No. 3, Op. 57 Nos. 1-3
Francesco Caramiello piano
The Philharmonia
Francesco D'Avalos
ASV CD DCA 691 (1990)
[flac, cue, log, scans]
Giuseppe Martucci
Piano Quintet, Op.45
Ottorino Respighi (1879-1936)
Piano Quintet
Five Lines
Amadeus AM 254-2 (2011)
[flac, cue, log, scans]
Giuseppe Martucci
Symphony No. 2, Op. 81
Andante, Op. 69 No. 2 for cello and orchestra
Colore Orientale, Op.44 No. 3
George Ives cello
The Philharmonia
Francesco D'Avalos
ASV CD DCA 689 (1990)
[flac tracks, cue, log, scans]
Giuseppe Martucci
Piano Trios Op. 59 & Op. 62
Trio Modigliani
aka Trio Metamorphosi
Amadeus AM 249-2 (2010)
[flac, cue, log, scans]
Giuseppe Martucci
Complete Works for Cello and Piano:
Sonata Op. 52
Tre pezzi Op. 69
Due romanze Op. 72
Enrico Dindo cello
Andrea Dindo piano
Velut Luna CDCI 040A (2004)
[flac, cue, log, scans]
Also recommended:
Martucci: Symphony No. 1, Notturno, Novelletta, Tarantella
(F. D'Avalos)
Martucci: La canzone dei ricordi, Notturno - Respighi: Il tramonto
(B. Balleys mezzo-soprano, J. Lopez-Cobos)
Most of the composers mentioned in post # 1 were infact also composers of operas. Giovanni Sgambati and Giuseppe Martucci, on the contrary, never wrote for that genre. They promoted new music institutions in Italy and organized performances of German music: the Dante-Symphonie and Tristan und Isolde were premiered in Italy under the direction of Sgambati and Martucci respectively.
"Sgambati has composed two quintets which I consider the most remarkable works of this kind to have appeared in many a year" wrote Liszt in a letter from Rome and surely you should try them as well as Martucci's one. Their orchestral works are not many: for a first approach I would put aside the first Symphony of Sgambati and the first Piano Concerto of Martucci and enjoy the works posted here.
The Requiem probably deserves a second recording but in the meanwhile you can take this one:

Messa da Requiem
Joern Wilsing baritone
Philharmonischer Chor Heilbronn
Members of the Staatorchester Stuttgart
Ulrich Walddörfer
Carus 83.121 (1991)
[flac, cue, log, scans]
Courtesy of Nozomi

Symphony No. 2
Piano Concerto Op. 15
Martina Filjak piano
Orchestra Sinfonica di Milano Giuseppe Verdi
Francesco Attardi
Amadeus AM 304-2 (2015)
[flac, cue, log, scans]

Piano Quintets Nos. 1 & 2
String Quartets Nos. 1 & 2
Roberto Plano piano
Quartetto Noferini
Brilliant Classics 94813 (2015)
[flac, cue, log, scans]

Piano Concerto No. 2, Op. 66
Orchestral pieces Op. 55 Nos. 1-2, Op. 61 No. 3, Op. 57 Nos. 1-3
Francesco Caramiello piano
The Philharmonia
Francesco D'Avalos
ASV CD DCA 691 (1990)
[flac, cue, log, scans]
Giuseppe Martucci
Piano Quintet, Op.45
Ottorino Respighi (1879-1936)
Piano Quintet
Five Lines
Amadeus AM 254-2 (2011)
[flac, cue, log, scans]

Symphony No. 2, Op. 81
Andante, Op. 69 No. 2 for cello and orchestra
Colore Orientale, Op.44 No. 3
George Ives cello
The Philharmonia
Francesco D'Avalos
ASV CD DCA 689 (1990)
[flac tracks, cue, log, scans]

Piano Trios Op. 59 & Op. 62
Trio Modigliani
aka Trio Metamorphosi
Amadeus AM 249-2 (2010)
[flac, cue, log, scans]
Giuseppe Martucci
Complete Works for Cello and Piano:
Sonata Op. 52
Tre pezzi Op. 69
Due romanze Op. 72
Enrico Dindo cello
Andrea Dindo piano
Velut Luna CDCI 040A (2004)
[flac, cue, log, scans]
Also recommended:
Martucci: Symphony No. 1, Notturno, Novelletta, Tarantella
(F. D'Avalos)
Martucci: La canzone dei ricordi, Notturno - Respighi: Il tramonto
(B. Balleys mezzo-soprano, J. Lopez-Cobos)